Members of the Syrian Democratic Forces (SDF) deploy outside Ghwayran prison in Syria's northeastern city of Hasakeh, after having retaken the facility following its takeover by Islamic State (IS) group forces. January 26, 2022. AFP

Containing a Resilient ISIS in Central and North-eastern Syria

Its self-declared caliphate is gone, but ISIS continues to stage attacks and intimidate the public in much of its former domain. The forces fighting the group need to hinder the militants’ movement between Syria’s regions – and, above all, to avoid debilitating conflicts with one another.

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What’s new? ISIS is waging a resilient insurgency throughout central and north-eastern Syria. It treats these two quasi-independent zones as interconnected theatres, giving it flexibility in its strategy for reasserting territorial control. The myriad forces battling the group, meanwhile, often work at cross-purposes.

Why does it matter? Counter-ISIS campaigns have made significant yet inconclusive gains. In particular, they have done little to stop fighters from crossing the lines of control in Syria. The longer this situation persists, the deeper the militants can sink their roots and the harder they will be to beat.

What should be done? First and foremost, those fighting ISIS should avoid escalation among themselves that would give the group more breathing room. Each actor should also work to limit the militants’ freedom of movement between theatres, primarily by closing off smuggling routes.

Executive Summary

ISIS – the Islamic State in Iraq and Syria – has shown considerable resilience since March 2019, when it lost the last piece of territory it held in Syria and Iraq. It has maintained, and in some cases expanded, a robust insurgency in four parts of Syria, each held by a different set of Syrian forces, three of which have foreign backers. Its adversaries, who are often at odds with one another, have siloed their counter-ISIS efforts and done little to stop the movement of militants across the permeable lines of control. ISIS is exploiting this disorder to bolster its fighting capacity. Policymakers on the various sides conducting counter-ISIS operations appear to be a long way from forging a détente, but they should nonetheless strive to avoid new conflict among themselves, which could only serve ISIS. They should ensure that their strategies account for developments in regions outside their control. They should also crack down on the smuggling routes that ISIS uses to transport fighters and supplies from one theatre to another.

The Islamic State’s self-declared caliphate came to an end with its defeat in the Syrian town of Baghouz near the Iraqi border. Since then, a multitude of parties have taken over the land that once made up its domain: the Iraqi army and Popular Mobilisation (al-Hashd al-Shaabi) paramilitary groups in Iraq; the Kurdish-led Syrian Democratic Forces (SDF), backed by the U.S.-led Global Coalition to Defeat ISIS in north-eastern Syria (the U.S. also continues to launch airstrikes on ISIS targets in other parts of the country); Türkiye and its Syrian partners in northern Aleppo; the Islamist group Hei’at Tahrir al-Sham in Idlib; and the Damascus regime and its Russian and Iranian allies in the central Syrian desert known as the Badia.

Today, ISIS leaders appear mostly to be providing broad guidance through online messaging rather than exercising day-to-day command over all the group’s members and sympathisers in Syria. The group now seems to operate on two levels: a core of militants acting on the leadership’s directives conducts complex attacks, while a second, larger set of decentralised cells carries out smaller, more frequent raids, intimidates the public and handles the money. In this manner, ISIS has entrenched communication and transit networks linking the country’s various regions, assigning its cells specific roles in each place and viewing its activities in each area as enhancing those in the others. ISIS is readying itself to pursue the goal of regaining overt territorial control if and when circumstances allow.

In central and north-eastern Syria [ISIS] moves men and materiel between regime- and Syrian Democratic Forces-controlled regions.

ISIS uses each of its four zones of influence in Syria in a distinct way. In the Badia, the rear base for its operations in Syria, as well as Iraq, it also trains most of its new recruits. In the north east, it gathers funds and stores supplies, as it stages attacks on security forces, technocrats and tribal notables to weaken public confidence in local governance. In the north and north west, it maintains hideouts for mid-level and senior commanders, who enjoy a degree of anonymity among the hundreds of thousands of displaced Syrians living in makeshift settlements. The ISIS insurgencies in central and north-eastern Syria are particularly intertwined. The group moves men and materiel between regime- and SDF-controlled regions depending on its changing objectives, its logistical needs and its foes’ vulnerabilities in each area. These movements appear to be coordinated among central, regional and sub-regional commanders.

The ceasefires that froze Syria’s front lines in 2020 allowed Damascus and its external backers to redeploy troops to fight ISIS in the centre and east. This effort led to a drop in ISIS attacks on regime targets throughout 2021. Some ISIS fighters withdrew to even more remote parts of central Syria to avoid interdiction, while many others moved into Iraq or north-eastern Syria. This second cohort of fighters appears to have bolstered the cells in the latter areas, enabling ISIS to carry out more operations, including the spectacular January 2022 assault on the SDF-run prison in Hasakeh holding ISIS fighters and adolescent boys from Syria and Iraq, as well as third countries.

Omens of a large-scale ISIS attack had been visible for some time. Throughout much of 2020 and 2021, ISIS cells had been lying low in the north east, building an intelligence network, raising money through theft, extortion and smuggling, and degrading the SDF’s capacity to gather intelligence and provide services through its Autonomous Administration. The cells picked up the pace of their efforts in mid-2021, as their revenues grew.

SDF-held Syria is particularly vulnerable to a resurgent ISIS. The SDF, despite its earlier strides in battling the group, faces myriad problems that could derail counter-ISIS efforts and hamper its ability to guard the thousands of militants, as well as affiliated women, whom it holds in camps along with their children. ISIS cells are assassinating local SDF commanders and tribal notables, sowing fear in order to heighten their sway over people in areas the group previously controlled. In particular, the cells’ growing reach in Deir al-Zor has frightened residents, thwarting the SDF and U.S.-led coalition in efforts to collect intelligence. The SDF’s willingness and ability to counter ISIS is contingent on continued U.S. military support, and perhaps also lowered Turkish and regime threats to its rule.

Despite this unstable situation, those fighting ISIS can still prevent the group from resurging. Primarily, they will need to forgo conflict among themselves that could give ISIS a new lease on life. But they can do more than that.

In the north east, U.S.-led coalition members should expand their political and economic support, particularly where residents are at high risk of ISIS recruitment, such as Raqqa and Deir al-Zor, and increase material aid for and training of security forces. They should simultaneously push for reforms to policies in Arab-majority areas that have generated grievances of which ISIS takes advantage. With the U.S.-led coalition’s help, the SDF should also clamp down on corruption and smuggling.

Damascus and Moscow should likewise secure the lines of control in the Badia, as a stronger ISIS in the north east could soon try to bolster cells in the central desert with new recruits and supplies. The Badia’s oil and gas fields would be vulnerable to attack if ISIS were to return in significant numbers. The regime and its external backers should keep taking the fight to ISIS in central Syria. The group is unlikely to again pose the global menace it did when it ruled its caliphate some years ago. But in the right conditions, it could take advantage of the discord or distraction among its enemies to expand its military and financial reach and add misery to the lives of Syrians and Iraqis in areas where it operates.

Deir al-Zor/Hasakeh/Washington/Brussels, 18 July 2022

Map of Central and Northeast Syria, June 2022. Borders, roads, and water from Humanitarian Data Exchange (HDX); control areas adapted from @Suriyakmaps; oil, gas and infrastructure from Crisis Group database.

I. Introduction

Since its territorial defeat in central Syria in 2017 and in north-eastern Syria and northern Iraq in 2019, the Islamic State has waged a sophisticated insurgent campaign spread thinly across these regions of the two countries. The various actors controlling these areas rarely cooperate in their counter-ISIS efforts and in fact often work against one another, to the militant group’s benefit.[fn]Syria is divided into four de facto areas of control. The regime and its external backers rule almost 65 per cent of the country, including the south, the centre and the two biggest cities, Aleppo and Damascus. The Kurdish-led SDF controls the north east, the Islamist militant group Hei’at Tahrir al-Sham (HTS) administers Idlib province in the north west and Turkish-backed Syrian rebels run Afrin, northern Aleppo governorate and a strip of land along the Turkish border extending from Tel Abyad to Ras al-Ain.Hide Footnote  ISIS, by contrast, treats these border-spanning zones as interconnected theatres, creating a significant degree of flexibility in its strategy for reasserting its dominance there.[fn]In addition to operations in central, north-eastern and north-western Syria, ISIS has occasionally claimed attacks in Daraa and Quneitra governorates in the south. Such claims are rare, however, and it is unclear to what extent these cells are tied to the ISIS network in Syria. They may instead be remnants of a historically isolated ISIS affiliate that controlled parts of the Yarmouk river basin at the intersection of the Syrian, Israeli and Jordanian borders. Crisis Group telephone interviews, Daraa-based researchers, June 2021; Crisis Group interviews, U.S. military and security officials, Hasakeh, May 2021.Hide Footnote

Damascus, whose top priority has always been its fight with anti-regime rebels, did not launch a major counter-ISIS campaign until May 2017, once it had recaptured the country’s largest city, Aleppo, from the rebels and semi-frozen the front lines in that battle. Together with Russia and Iran, the regime went after ISIS on three fronts over the course of that month, beginning in eastern Aleppo governorate, then in eastern Homs and finally eastern Hama. By mid-September, these offensives had pushed ISIS fighters back to the Euphrates in central Deir al-Zor. On 28 September 2017, ISIS mounted its last serious counterattack upon regime forces, dubbed the “al-Adnani offensive”, briefly reaching the Damascus-Homs administrative boundary before withdrawing. On 9 November, Damascus announced the defeat of ISIS west and south of the Euphrates.[fn]Al-Boukamal city declared fully liberated”, Syrian Arab News Agency, 9 November 2017.Hide Footnote

At around the same time, the Syrian Democratic Forces (SDF), the armed wing of the Kurdish-led Autonomous Administration that runs much of north-eastern Syria, was entering the third straight year of its anti-ISIS operations, having just retaken Raqqa, a city on the Euphrates. From late 2017 through March 2019, the SDF, backed by the U.S.-led Global Coalition to Defeat ISIS, gradually seized the remaining ISIS-controlled territory in eastern Deir al-Zor, along the Euphrates’ north-eastern bank. Forced to operate as an insurgency in central Syria, ISIS fighters periodically harassed regime, Russian and Iranian units in regime-held areas in western Deir al-Zor, eastern Homs and southern Raqqa.

After its final territorial defeat in Baghouz in March 2019, ISIS shifted to insurgent tactics.

After its final territorial defeat in Baghouz in March 2019, ISIS shifted to insurgent tactics in the north east as well. Its modus operandi has been mixed, combining the efforts of veteran units under central command with those of far-flung cells that appear to take their guidance from the group’s media signalling.[fn]Crisis Group interviews, SDF and U.S.-led coalition security officials, Hasakeh and Raqqa, 2021.Hide Footnote  ISIS has thus been able to maintain a drumbeat of small-scale operations in SDF-controlled areas. With these roadside bombings, drive-by shootings and assassinations, mainly of Arabs close to the SDF, as well as through extortion, it has instilled widespread fear. ISIS has concentrated its attacks in certain parts of Deir al-Zor, but it has also harried areas farther to the north and west, such as southern and eastern Hasakeh district, the Raqqa countryside and the town of Manbij.

These constant, low-level attacks reached a higher pitch in early 2022, when ISIS fighters assailed the al-Sinaa prison in Hasakeh and subsequently entered a two-week street battle with SDF units in the adjoining neighbourhood of Ghowayran. The scale of the jailbreak, just two months after the SDF had uncovered a similar plot, raises serious concerns about the militant group’s ability to thrive in unstable parts of the country and pull off deadly and strategically important operations.[fn]Crisis Group interviews, SDF commanders, Qamishli and Hasakeh, March 2022.Hide Footnote

This report maps the complex reality of ISIS’s enduring presence in Syria, focusing on the country’s centre and north east. It is based on research in the four separately controlled parts of Syria through more than a hundred in-person and remote interviews with Syrian regime security and military officers, the SDF and allied forces, the Islamist militants Hei’at Tahrir al-Sham (HTS), the Turkish-backed Syrian National Army and other individuals in both central and north-eastern Syria, as well as U.S. officials. It also reflects in-person interviews with former ISIS fighters and sympathisers in Syria. The report’s discussion of ISIS activities in central Syria draws on ISIS media, as well as pro-regime media reports of ISIS attacks and military deaths, along with weekly interviews with several regime combatants deployed to, or in contact with friends stationed at, central Syrian fronts.[fn]Crisis Group analyst’s research in a previous capacity. The data were compiled in a spreadsheet, tracking both attacks claimed by ISIS and those reported publicly and privately by pro-regime sources since 2018. A full discussion of the methodology appears in Gregory Waters and Charlie Winter, “Islamic State Under-Reporting in Central Syria: Misdirection, Misinformation or Miscommunication?,” Middle East Institute, 2 September 2021.Hide Footnote

A separate Crisis Group briefing will focus on ISIS activities in north-western Syria, an area facing distinct challenges. HTS, the dominant force in Idlib, has managed to suppress most of the militants’ attempts to build an active network there, especially since the March 2020 Turkish-Russian ceasefire. Yet the numerous, loosely governed informal displacement camps are a major security concern. In Turkish-backed rebel-held zones in northern Aleppo, as well as in points east brought under Turkish control by Operation Peace Spring in 2019, ISIS retains a presence. Its elements are taking advantage of competition among Syrian rebel groups and an incoherent security structure to find transit routes and temporary refuge. In mid-July, a U.S. airstrike killed a top ISIS commander in the north west[fn]“U.S. says airstrike kills ISIS leader in Syria”, NBC News, 12 July 2022.Hide Footnote .

II. Countering ISIS in the Badia

The swathe of desert in central Syria known as the Badia has become a staging area for ISIS insurgencies in both north-eastern Syria and Iraq. Since it lies in nominally regime-controlled territory, it is also an important foothold for ISIS in and of itself.[fn]ISIS has stated that “the valleys of the Levant [Syrian Badia] are now military bases and law schools”. It has said the fighters in the Badia are “at a stage close to that in which their brothers lived in the Iraq valley in the past … [whose] sunken camps in the depths of the desert were, after years, a major step toward the cities and the renewal of the structure of the Islamic State”, Al-Naba, August 2021 (Arabic). Copy on file with Crisis Group.Hide Footnote  A remote expanse of sand and rock, the Badia stretches from the eastern Homs countryside to the Euphrates and from the Iraqi border to the southern Aleppo hinterland, encompassing much of Homs, north-eastern Hama, southern Raqqa and western Deir al-Zor governorates. Western analysts and policymakers have long overlooked its significance, partly because they have difficulty obtaining accurate information from the area. The Syrian army, Russia and Iran have been fighting ISIS in the Badia for four years, finding some success only in 2021.

The Badia has served as ISIS’s rear base since at least 2019. The group has stored weapons and supplies in the desert, set up training camps and established safehouses to which fighters and commanders retreat when under pressure on other fronts.[fn]Crisis Group telephone interviews, SDF commanders and U.S.-led coalition officials, July 2020 and May 2021. Follow-up telephone interviews with a regime security officer in January 2022 and SDF security officers in Hasakeh in March 2022 confirmed that ISIS was still using the Badia for these purposes. The officers suspect, however, that the training camps have shrunk over the past year, along with the number of recruits moving through them, as a result of regime pressure.Hide Footnote  For the time being, its strategic goal in central Syria seems to be to defend these assets while preventing regime forces from getting a firmer grip on the region. To that end, ISIS cells began to regularly harass the Syrian army and allied militias in early 2020, operating both in coordination and independently when necessary.[fn]According to an ISIS sympathiser in the Badia, “The cells are scattered in the Syrian-Iraqi Badia and there are no safe, secure and direct corridors to hold meetings. Large numbers of Russian and Iranian spy trucks and drones monitor radio waves and channels, so there are no secure communications either. The cells and supporters understand the [organisation’s] general goals and targets, and carry out their attacks and raids according to these strategies. Nowadays, the ISIS cells manage their jihad on a day-to-day basis. Sometimes, they disappear; at other times, they carry out big attacks that reach al-Mayadin town, and the road from Palmyra to Deir al-Zor through Shula and Sukhna. They target regime and [allied] militia checkpoints and seize their arms, oil products and foodstuffs to support their families and fighters”. He further stated that “Cells do not take orders from ISIS central command”, though Crisis Group could not verify this claim independently, or even that ISIS has a central command. Crisis Group interview, Deir al-Zor, September 2021. (The Iraqi Badia connects to the Syrian Badia via Iraq’s Anbar governorate.)Hide Footnote  Significant regime, Russian and Iranian anti-ISIS operations in the first half of 2021 forced ISIS cells to withdraw deeper into the Badia. While ISIS activity in central Syria has diminished accordingly, the group has not changed its overall strategy in the country and continues to conduct intermittent but deadly attacks on regime forces.

Figure 1: IS activity in Central Syria. Incidents per month, 3-month moving average. Crisis Group database.
Figure 2: IS attacks by governorate. Incidents per month, 3-month moving average. Crisis Group database.

A. ISIS’s Resurgence (2019-2021)

ISIS laid the groundwork for reviving its insurgency in central Syria as soon as it began losing territory to the regime and its Russian and Iranian allies in 2017.[fn]Crisis Group telephone interviews, regime-affiliated soldiers in central Syria, 2020.Hide Footnote  For the first few years, these cells appear to have operated in a highly decentralised structure. While attacks occurred in the Badia as early as October 2017, ISIS started to claim some of them only in mid-2018. During late 2017 and early 2018, it focused on the urban belt along the Euphrates’s western bank between Mayadeen and Boukamal rather than on the more remote southern Raqqa and eastern Homs governorates.[fn]Since losing control of the Badia, ISIS has produced extremely little media reporting on its activities there. A 2021 study found that only 25 per cent of the group’s attacks in 2020 occurred in the Badia, while pictures and videos of its activities have been rarer still. Since July 2021, ISIS has only claimed three operations in central Syria, despite more than 160 verifiable reports of attacks on security personnel and civilians in that same period.Hide Footnote  In 2018, ISIS took advantage of the regime and Russian preoccupation with major offensives in Damascus, Daraa and Idlib to gradually expand its presence outside Deir al-Zor to eastern Homs, a more central and mountainous area providing access to southern Raqqa and eastern Hama.[fn]The Syrian regime began its final offensive in East Ghouta, a rebel-held Damascus suburb, in February 2018, achieving victory on 11 April. One week later, ISIS fighters who controlled the southern Damascus neighbourhood of Yarmouk launched their own small offensive, seizing from the regime the adjacent district of Qadam. In response, regime forces launched a new offensive there, forcing the remaining ISIS fighters to surrender in May. Between June and July, the regime moved most of the forces it had gathered in Damascus to Daraa, where it moved against the remaining rebel-controlled towns in the governorate, as well as the small ISIS-held pocket in the Yarmouk basin in south-western Daraa, which surrendered in late July.Hide Footnote  From there, it appears to have spent the second half of 2018 rebuilding its southern Raqqa networks, continuing into 2022.[fn]Assessment based on analysis of reported ISIS attacks across the Badia in 2018 and 2019, which showed an increase in eastern Homs in late 2018 and gradually more consistent attacks in southern Raqqa in early 2019. In July 2018, ISIS fighters deported by the Syrian regime from southern Syria a month earlier, after the regime offensive there, launched an insurgency in the Suwayda countryside. The regime defeated them in December 2018 and these fighters had no apparent impact on the broader Badia insurgency. Crisis Group data gathered by analyst in previous capacity from pro-regime Facebook pages announcing ISIS attacks and victims.Hide Footnote

ISIS stepped up resource allocation to, and more direct command of, the Badia cells after its March 2019 territorial defeat in Baghouz. Attacks in western Deir al-Zor and Homs reached a nearly one-year high in April 2019 and ISIS cells seized new territory for the first time during their insurgency when they expelled regime forces from Jabal Bishri, the highlands at the crossroads of Raqqa, Deir al-Zor and Homs. Over the rest of 2019, ISIS gradually expanded its operations across eastern Homs and western Deir al-Zor and its previously sporadic activity in southern Raqqa became more sustained.[fn]In January 2020, ISIS claimed its first attack in southern Raqqa, despite sporadic attacks occurring in the area since October 2017. This claim suggests that cells operating there had become more robust and better integrated into the broader ISIS network by that time. ISIS activity in southern Raqqa further increased throughout 2020, with the group carrying out at least 49 attacks. These new attacks occurred across the governorate’s southern half, from the oil fields near the Deir al-Zor administrative border to the strategic Resafa crossroads to the Anbaj junction along the Raqqa-Aleppo boundary. Crisis Group data gathered by analyst in previous capacity from pro-regime Facebook pages announcing ISIS attacks and victims, and ISIS online media.Hide Footnote

Building on this foundation, the group surged outward to the Badia’s edges in eastern Hama and southern Aleppo in the first half of 2020, and then escalated its activity across the region in the second half of the year.[fn]In October 2017, the Syrian regime and its allies defeated ISIS cells that had long been rooted in the Uqayribat and Salamiya countryside of eastern Hama governorate, forcing them to withdraw across Syrian army lines. From their new positions, they started attacking HTS in south-eastern Idlib. The first confirmed ISIS attack in eastern Hama after this defeat occurred more than two years later, in November 2019, when ISIS media published pictures of fighters firing upon regime paramilitaries near Jubb ‘Awar, in the governorate’s south east, just north of the Shair gas field in Homs. Another minor attack occurred that December, after which confirmed activity in the governorate ended for three months. ISIS cells picked up the pace of operations beginning in April 2020, conducting attacks with explosives and small arms, and assassinating local commanders in the Ithriya-Rahjan corridor in the governorate’s north east, close to Aleppo and Idlib governorates. Regime security forces viewed this area as highly secure at the time and the repeated attacks demonstrated a high degree of infiltration by ISIS cells. In June 2020, ISIS cells expanded their presence, briefly seizing two villages west of Uqayribat, even deeper behind “secure” regime lines. Over the rest of 2020, ISIS activity in the governorate continued to escalate, with attacks focused in the Rahjan area, Ithriya and Uqayribat. Crisis Group data gathered by analyst in previous capacity from pro-regime Facebook pages announcing ISIS attacks and victims, and ISIS online media, 2020.Hide Footnote  Attacks increased in both frequency and complexity, with cells assassinating regime, Iranian and Russian commanders, conducting ambushes along major highways and targeting civilians in Homs, Hama, Aleppo and Raqqa.[fn]Crisis Group data gathered by analyst in previous capacity from pro-regime Facebook pages announcing ISIS attacks and victims, and ISIS online media, 2020.Hide Footnote

As ISIS expanded its operations in 2019 and 2020, its fighters relied on exchange with civilians to survive in the barren Badia.

As ISIS expanded its operations in 2019 and 2020, its fighters relied on exchange with civilians to survive in the barren Badia. ISIS cells traded with residents of eastern Homs and Deir al-Zor, acquiring much needed basic goods.[fn]Crisis Group telephone interviews, National Defence Forces (NDF) officer deployed to eastern Hama and residents of eastern Homs, 2021; and SDF officials, Raqqa, March 2022.Hide Footnote  But they also resorted to crime: fighters in eastern Hama often stole livestock from shepherds. Cells also raised funds by allegedly shaking down a Syrian oil baron close to Damascus. Acting as a middleman for the regime, this person has allegedly dealt with ISIS throughout its existence, buying oil from the group when it held the wells, and then paying it (on the regime’s behalf) to refrain from attacking the fields or his trucks after it lost control in 2017.[fn]Crisis Group telephone interview, NDF officer overseeing anti-ISIS operations in central Syria, January 2022.Hide Footnote

Yet, as Syria’s economy continued to deteriorate in 2021, so did local trade and, with it, ISIS’s ability to acquire basic necessities.[fn]War has severely depleted Syrian government revenues, along with decades of rampant regime corruption and Western sanctions. See “U.S. Sanctions on Syria: What Comes Next?”, Crisis Group Commentary, 13 July 2020.Hide Footnote  Throughout 2021, civilians in eastern Homs and rural areas of western Deir al-Zor migrated to urban centres in western Syria or along the Euphrates, removing key trading partners for ISIS cells.[fn]Crisis Group telephone interview, NDF officer overseeing anti-ISIS operations in central Syria, January 2022.Hide Footnote  In Deir al-Zor, Iran’s Islamic Revolutionary Guard Corps (more precisely, a group of Iranian officers supported by Afghan, Pakistani and Syrian fighters) has reportedly expanded its presence from Boukamal into Mayadin, co-opting local merchants along the way, putting further pressure on trade upon which ISIS cells had relied.[fn]According to a NDF officer overseeing anti-ISIS operations in central Syria, “The recent economic decline has also affected a lot of the merchants ISIS was trading with. Most of the remaining merchants either are under direct Local Defence Forces or Islamic Revolutionary Guard Corps’ control or are too poor to have anything to trade”. Crisis Group telephone interview, January 2022. The Local Defence Forces are a network of Syrian militias under Iranian command and paid by Tehran.Hide Footnote

New military deployments and transport policies adopted by the regime early in 2021 also hurt ISIS’s financial operations. Civilian and commercial vehicles began passing through central Syria in convoys escorted by Syrian army and Syrian or Russian helicopters.[fn]Crisis Group telephone interview, NDF officer overseeing anti-ISIS operations in central Syria, January 2022.Hide Footnote  This new policy ended ISIS attacks on highways, while the regime and Russia were able to reinforce protection of the Badia’s small oil and gas fields.[fn]Crisis Group data suggest that there were only two successful ISIS attacks on highways in central Syria in 2021. A January attack destroyed a bus and several oil tankers and trucks in eastern Hama; an attack the next month blew up an oil truck with an explosive device in Homs. ISIS carried out a major attack on a civilian convoy and its security escort travelling on a secondary road far from major highways in eastern Hama in April 2021.Hide Footnote

The regime’s security measures largely mitigated the threat ISIS had posed to oil trucks and fields in 2020, reportedly allowing the aforementioned businessman to stop paying protection money to ISIS. This development appears to have triggered a shift in ISIS’s strategy, with the group sending cells into north-eastern Syria and Iraq, where daily life is easier, while its remaining Badia fighters stepped up attacks on energy infrastructure.[fn]Crisis Group telephone interview, NDF officer overseeing anti-ISIS operations in central Syria, January 2022. This shift is also visible in the targets ISIS attacked in 2021, highlighted by the September attack on the major power plant outside Damascus, which ISIS claimed as part of its “economic war on the regime”, and further demonstrated by attacks on oil field workers, guards and pipelines across central Syria in February, March, April, June and December 2021. Crisis Group data gathered by analyst in previous capacity from pro-regime Facebook pages announcing ISIS attacks and victims, and ISIS online media, 2021.Hide Footnote  New security measures and a general increase in local awareness also made it more difficult for ISIS to steal sheep in eastern Hama, a vital source of food and financing for its cells in late 2020.[fn]Crisis Group telephone interview, NDF officer overseeing anti-ISIS intelligence operations in central Syria, January 2022. Crisis Group data support this claim, showing a high number of ISIS attacks on civilians in eastern Hama in late 2020 and early 2021, and an overall drop in attacks in Hama in the second half of 2021. Data gathered by analyst in previous capacity from pro-regime Facebook pages announcing ISIS attacks and victims, and ISIS online media, 2021. An Asayish (Kurdish security) commander in Raqqa said selling stolen sheep is a major source of income for ISIS in north-eastern Syria. Crisis Group interview, Raqqa, March 2022.Hide Footnote  The country’s economic collapse has further hampered ISIS’s ability to trade, as many merchants either have left the Badia for larger cities or no longer have access to the basic goods that ISIS cells used to acquire.[fn]Crisis Group telephone interview, regime officer working with units deployed in eastern Homs, January 2022.Hide Footnote  The loss of local supplies increased the importance of logistical lines for ISIS cells in the Badia to other areas, like Raqqa.

Yet the regime and its allies have not achieved complete success, as ISIS cells in the Badia have shown a persistent ability both to fend off attack and to conduct both simple and complex offensive operations.[fn]Simple operations include indiscriminate mine or explosive device attacks – such as when regime forces drive into minefields where no ISIS fighters are present at the time – harassment fire of regime patrols and quick ambushes that cause no regime losses. Complex operations are those that involve gathering intelligence to assassinate high-value targets, penetrating deep within regime territory, capturing regime positions, setting up fake checkpoints, striking from multiple points of attack and/or combining explosive devices or mines with small- or heavy-arms assaults on regime forces.Hide Footnote  Their ability to operate both independently or under the direction of regional or sub-regional commanders gives each cell considerable latitude in choosing when and where to strike. Their agility is all the greater because ISIS has kept its cells in central Syria small, at fifteen to 25 men, each subdivided into four-to-five-man teams that, in past years, often operated out of a single pickup truck.[fn]Crisis Group interview, ISIS sympathiser, Deir al-Zor, August 2021.Hide Footnote

Until 2021, ISIS had largely avoided losing fighters and materiel to regime and Russian attacks thanks to its flexible command-and-control system.[fn]Equipping cells with pickup trucks meant that the units could easily run away from approaching regime forces while carrying supplies to survive for extended periods away from safehouses. The trucks also allowed cells to carry heavy weapons, as they are commonly mounted with anti-aircraft guns, rockets or heavy machine guns. ISIS uses these to harass regime forces from afar, providing an extra layer of protection while attacking. ISIS published numerous videos and pictures of its central Syria fighters in 2019 and 2020 that showed these vehicles. Nearly every truck was mounted with a heavy weapon and filled with bags of supplies and water and gas cans. Yet increased air support and intense battles in early 2021 led to the destruction of many of ISIS’s trucks to the point that regime forces reportedly encountered no such vehicles in 2021. Instead, ISIS militants have relied on dirt bikes for transport and for hit-and-run attacks. Crisis Group telephone interview, regime security commander, January 2022.Hide Footnote  As the regime ratcheted up its pressure in 2021, ISIS fell back on its most basic small-unit structure to survive. These units dispersed across the Badia, moving among camps to avoid detection.[fn]A regime officer working with units deployed in eastern Homs said dugout camps discovered by regime security forces usually consist of four to five holes that can hold one or two people each, surrounded by several smaller holes for food and weapons storage. These holes are covered with flat metal sheets and disguised with sand and brush, making them nearly impossible to spot from the air. Crisis Group telephone interview, January 2022.Hide Footnote  Thus on the run, ISIS carried out fewer and less effective attacks in 2021 than in the preceding year. The influx of pro-regime forces into central Syria in 2021 has also hampered, though not eliminated, ISIS militants’ ability to move freely close to towns and highways.

Life returns to Raqqa despite the continued need for reconstruction, Syria. March 2022. CRISIS GROUP / Gregory Waters

B. Insufficient Response

Damascus did not take serious note of the growing ISIS insurgency until the second quarter of 2019, when its forces started to take significant losses. Over the course of seven days in mid-April, ISIS cells in Deir al-Zor and Homs killed at least 32 soldiers and pro-regime militia members. In one of the most serious attacks, which prompted Damascus to debate reinforcing the Badia with fresh troops and airpower, ISIS militants encircled members of the army’s 14th special forces division near the Kawm oasis in eastern Homs, killing the commander and twelve of his men. The following day, ISIS ambushed search parties, who survived only after reinforcements broke the ISIS siege following two days of fighting.[fn]Crisis Group data gathered by analyst in previous capacity from self-reported regime losses, 10 November 2017-31 March 2020.Hide Footnote  While this attack forced Damascus to acknowledge the problem in Homs, the army’s high command decided against a large operation to clear Jabal Bishri, citing a lack of air support due to an offensive in north-western Syria it had planned for the following month.[fn]Crisis Group telephone interview, regime officer, April 2019.Hide Footnote

As the ISIS insurgency grew throughout 2019, Syrian soldiers became the main victims of the regime’s ineffective counter-ISIS strategy. Damascus continued to limit patrols to the Badia’s more populated areas, providing the militants with the room they needed to move additional resources into the region. In mid-2019, Palmyra-based National Defence Forces (NDF) fighters spoke frequently of more than 30 soldiers being killed or going missing each week, as their patrols came under attack from ISIS cells seeking to tighten their hold on eastern Homs.[fn]Crisis Group telephone interview, NDF officer in Hama who spoke regularly with NDF fighters in Palmyra, July 2019.Hide Footnote  The same paramilitaries complained that commanders sent men into the desert without proper supplies, equipment or intelligence briefings, and then neglected to give them sufficient reinforcements or artillery and air support once ISIS had engaged them.[fn]Ibid.Hide Footnote

The collapse of rebel front lines in Idlib and western Aleppo in February 2020 and the subsequent ceasefire mediated by Russia and Turkey could have enabled the regime and Russia to commit additional resources to the counter-ISIS campaign in central Syria.[fn]Crisis Group Middle East Report N°213, Silencing the Guns in Syria’s Idlib, 14 May 2020.Hide Footnote  Yet the Syrian army and air force were slow to make this transition, at first redeploying only small numbers of auxiliary units, mostly consisting of militiamen and poorly trained soldiers. Neither Russia nor the regime carried out regular airstrikes on ISIS targets until late 2020. Even then, these strikes mainly hit fixed locations in the desert, rather than moving live targets, and took place only after ISIS had attacked regime forces nearby.[fn]Crisis Group telephone interviews, several regime soldiers deployed throughout the Badia, April 2021.Hide Footnote  It was not until late 2020 and early 2021 that the regime began sending significant reinforcements and airpower to central Syria.[fn]The reason for the delay is unclear. The regime may have been waiting to see if the Idlib ceasefire would collapse.Hide Footnote

Instead, the regime’s primary response to the growing insurgency in 2020 was to replace the small patrols of 2019 with large-scale sweeps.[fn]These sweeps usually consisted of pro-regime units driving through dozens of empty hamlets and across hundreds of square kilometres over the course of three to fourteen days. Unit members would often list these “cleared” areas on their Facebook pages. See, for example, tweet by Gregory Waters, analyst, @GregoryPWaters, 6:50pm, 4 June 2020.Hide Footnote  The first significant Russian operation in the Badia occurred in February 2020, when Russian ground and air forces assisted regime units in clearing Jabal Bishri. This operation and an earlier one that included south-eastern Homs led ISIS activity to drop off perceptibly in February and March. Despite concerted Russian efforts, however, few ISIS fighters were killed or captured, and within two months, the cells had reconstituted themselves elsewhere in the Badia.

Most sweeps [by the Syrian regime and its backers] in 2019 and 2020 lacked air support, making them easy targets for ISIS ambushes.

The sweeps were an improvement, but they, too, sputtered at first due to a lack of manpower and coordination. From late 2019 through late 2020, the regime did not have the wherewithal to conduct large operations across the entire Badia, as it had deployed the bulk of its forces to the front in Idlib. Anti-ISIS operations at this time were led by a mix of militias and low-tier army units, chief among them the Russian-backed Liwaa al-Quds militia, local NDF units and the army’s 11th, 17th and 18th divisions.[fn]Liwaa al-Quds emerged from among pro-regime Palestinians in Aleppo in October 2013, waging warfare in and around the city. In 2019, pictures emerged online showing members of the group receiving training from Russian private contractors. See tweet by Gregory Waters, analyst, @GregoryPWaters, 5:09am, 27 January 2019. The NDF was established in 2012 through a joint effort of the Syrian army, local militias and Iranian officers, with the intent to form self-defence units to protect particular areas from rebel encroachment. The NDF network spans all of regime-held Syria and has a central command, but each NDF centre, or unit, operates with a high degree of autonomy. There are six main NDF centres in the Badia: the Palmyra, Sukhna and Badia centres in eastern Homs, the Deir al-Zor centre, the Salamiya centre in eastern Hama, and the Raqqa centre in southern Raqqa. There was little coordination between these centres and locally-based army units in 2019-2020. Crisis Group analyst’s interviews in previous capacity, NDF officers, 2020. The Syrian army’s 17th and 18th divisions are the lowest tier. Tasked with securing Syria’s north east prior to the civil war, the two divisions have always received the least support from Damascus, and both were decimated in the first wave of ISIS conquests in 2014 and 2015. The 17th division regularly flew in new recruits, mostly conscripts and petty criminals from western Syria, to its headquarters in Deir al-Zor throughout 2019 and 2020. The 11th division has a slightly better record and has fought throughout Homs for the entire war, but its officer corps was significantly degraded during these battles. In the Badia, the division’s units patrol the eastern Homs region from Palmyra to the Syrian-Iraqi border.Hide Footnote  Backing up these combined forces were other militias linked to regime intelligence agencies, and both Syrian and Russian private contractors who guarded oil and gas infrastructure.[fn]Crisis Group interviews, regime officers deployed in central Syria, 2021; and Russian oil workers’ VKontakte social media accounts showing them present in these fields. Pro-regime Facebook pages support claims of Russian involvement in securing and operating oil and gas fields in central Syria. See tweet by Gregory Waters, analyst, @GregoryPWaters, 2:11pm, 29 August 2020.Hide Footnote  Most sweeps in 2019 and 2020 lacked air support, making them easy targets for ISIS ambushes.,

ISIS was able to dodge the sweeps thanks to having spread its cells across the Badia since 2018 and established safehouses and weapons caches prior to that. Whenever the regime’s troops approached, the cells could simply move into nearby areas where few if any soldiers ventured on patrol. ISIS also launched its own offensive in April 2020, when its attacks doubled, striking security forces in several locations around and on Jabal Bishri, in eastern and south-eastern Homs, and deep inside territory the regime had thought secure in eastern Hama.[fn]Aside from a dip in reported attacks in June 2020, ISIS activity held steady at this level until it surged once more in August of that year. Crisis Group data gathered by analyst in previous capacity from self-reported regime losses, and ISIS claims, 2020.Hide Footnote  ISIS trained its sights on areas where the group had long been active in eastern Homs and western Deir al-Zor.

There is no clear logic as to why neither Russia nor the regime deployed better trained soldiers or warplanes to the Badia until late in 2020.[fn]Russia and Iran began making small adjustments to their respective Badia strategies in the second half of 2020. Following the first ISIS attack near Rahjan in April 2020, the Russian command organised a series of short sweeps by one of its proxies, the Mahrada and Suqaylabiya NDF. Beginning in June 2020, Iran focused almost exclusively on Deir al-Zor, gradually widening the presence of its main force, the Liwaa Fatemiyoun. These Afghan fighters, under the Revolutionary Guards’ command, manned outposts and patrolled the Boukamal countryside along the Iraqi border. But they also maintained a small presence along the highway connecting Deir al-Zor with Palmyra, where they have a headquarters. Crisis Group telephone interviews, NDF members deployed in Deir al-Zor and Palmyra over the course of 2020; and Crisis Group analyst’s interviews in previous capacity, regime fighters, 2020.Hide Footnote  One reason may be that neither expected, or wanted, the Idlib ceasefire to hold, and both were therefore uneasy about diverting airpower or troops from the north-western front. Internal politics may have also played a role, as the central Syria front spans several governorates and military sectors, each under the command of different officers. Poor communication among the various headquarters and personal disputes among officers may have prevented the joint operations that would have been necessary to push back ISIS cells.

Mid-2020 events in Deir al-Zor offer an illustration of how internal fissures could hamper a cohesive response. Major General Ghassan Mohammad, the Deir al-Zor Security and Military Committee commander and ostensible head of all regime forces in the governorate in 2020, sought to reinforce his authority by pressing the NDF’s Deir al-Zor centre to merge with his army command structure, triggering a series of local power struggles between the army and NDF.[fn]Damascus sent poorly trained and equipped forces. For example, in Deir al-Zor, the regime sent several hundred Damascus NDF members, many of whom were from formerly rebel-held towns and who had recently “reconciled” with the regime. In Hama, members of the 5th corps’ weakest and most poorly trained unit, the 7th brigade, were deployed to secure the area around Rahjan, a village on the Hama-Aleppo boundary that ISIS had repeatedly attacked since mid-2020. See Kayla Koontz and Gregory Waters, “Between the Coalition, ISIS and Assad: Courting the Tribes of Deir ez-Zor”, Middle East Institute, 3 November 2020.Hide Footnote  The spats led the army to withdraw from some of its posts, leaving the NDF exposed and unsupported in Deir al-Zor’s outlying rural areas. ISIS took advantage, targeting these positions and giving itself nearly free rein along the governorate’s main highways and smuggling routes.

It was not until General Mohammad, an Alawite from the coast, who according to local NDF fighters, was hostile toward Sunni Muslims from Deir al-Zor, was replaced by his second-in-command, Major General Nizar Khader, on 8 December 2020 that the army and NDF began to work together.[fn]Gregory Waters, “A new general and a fragile peace in Deir ez-Zor”, Middle East Institute, 19 April 2021.Hide Footnote  Khader hailed from a local tribe and spent his first months in power meeting regularly with tribal leaders, often along with the NDF commander. He did not press the NDF to integrate into the army command, organising joint patrols with it instead.[fn]Crisis Group analyst’s interviews in previous capacity, NDF officers, 2021.Hide Footnote

C. The Regime Pushes Back

Improved army-NDF relations in Deir al-Zor coincided with the decision by the Russian and Syrian army high command to dedicate the ground and air forces they needed to fight ISIS in central Syria. The turning point came on the night of 30 December 2020, when ISIS cells ambushed three buses carrying 4th armoured division soldiers on the M20 highway near Deir al-Zor city.[fn]The 4th armoured division was Syria’s premier fighting force before the war, and while its capabilities have suffered, it remains one of the most formidable units.Hide Footnote  The attack, which left at least 31 dead and seventeen wounded, highlighted the extent to which ISIS had infiltrated the countryside between the highway and Jabal Bishri over the past year. In response, Damascus quickly organised what would become its largest counter-ISIS operation since 2017, unifying forces from the army, NDF, Republican Guard and Liwaa Fatemiyoun, supported by the Russian air force.[fn]Crisis Group analyst’s interviews in previous capacity, NDF officers, 2021.Hide Footnote

ISIS also adopted new tactics during this offensive. Past regime operations had never lasted more than one or two weeks and ISIS often retreated before them rather than fight. But this time, ISIS forces stood their ground, engaging in a nearly three-month battle with regime and allied forces around Jabal Bishri.[fn]The fighting around Jabal Bishri was documented on numerous pro-regime community and unit-affiliated Facebook pages. See, for example, tweet by Gregory Waters, analyst, @GregoryPWaters, 26 February 2021. Crisis Group telephone interviews, NDF officer and local pro-regime militiaman, January-April 2021.Hide Footnote  By the end of March 2021, ISIS had begun to scale back its attacks on the regime, which had become increasingly risky due to more consistent use of Russian and Syrian airpower and the larger concentration of ground forces in the Badia. As cells became less active or left the Badia altogether, the rate of ISIS attacks returned to the early 2020 levels of ten to twenty per month throughout the rest of the year.[fn]Crisis Group data gathered by analyst in previous capacity from self-reported regime losses, and ISIS claims, 2021.Hide Footnote

The first operations of 2021 succeeded in pushing ISIS back from the highways and towns in much of the Badia, but it was the deployment of significantly more soldiers to the region throughout the spring that prevented the militants’ cells from reinfiltrating these areas. By April, the regime had begun winding down the Jabal Bishri operation, replacing its vulnerable patrols with a series of fortified outposts and dispatching better trained and equipped units to both the Homs and Deir al-Zor fronts. These soldiers came from bases in Damascus and north-western Syria, bringing with them tanks and armoured vehicles. It was the first major deployment of the army’s more competent units to central Syria.

Russia and Iran followed suit, building up their own and allied forces, and increasingly coordinating with each other and with Damascus. In 2021, Russia began sending NDF units and the Syrian army’s 5th corps and 25th division on more frequent patrols in eastern Hama and southern Aleppo, where ISIS cells had been preying on the population.[fn]Units of the Russian-commanded Syrian 25th army division have been frequently patrolling the area between Ithriya, Hama and Khanasir, Aleppo. By mid-2021, these sweeps had extended east toward the Maskanah plains in Aleppo and south to Raqqa’s Dibsi Afnan. Many of the soldiers involved in these operations are recent recruits from eastern Aleppo tribes. Crisis Group telephone interviews, 5th corps officers and NDF officer who had been deployed to east Hama, June 2o21; and Crisis Group assessment from open-source pro-regime media (see, for example, tweet by Gregory Waters, analyst, @GregoryPWaters, 12:55pm, 23 April 2021).Hide Footnote  At the same time, Iran expanded its role both within and outside Deir al-Zor. The Jabal Bishri offensive marked the first major deployment of Republican Guards and affiliated non-Syrian militias outside south-western Deir al-Zor since the regime and its allies first recaptured the area from ISIS in 2017. More than a thousand Fatemiyoun militiamen then moved south, clearing the countryside around Mayadin from late April to August.[fn]Attacks in the Mayadin countryside – at one time the most active region of western Deir al-Zor – have been nearly non-existent since the Afghan fighters moved in, as ISIS cells were forced to pull back deep into the desert along the Homs-Deir al-Zor border or into Iraq. ISIS did not renew its activity in Deir al-Zor until late July 2021, when some of the nearly 300 militants who had reportedly moved into Iraq in the previous months returned.Hide Footnote  The Iranian-led forces received Russian air support in both operations. In Homs, Afghan fighters reinforced newly built regime positions in Kawm, north east of Sukhna, and expanded into the desert south and south east of Palmyra from 2021 into early 2022.[fn]In August 2021, the bulk of the Liwaa Fatemiyoun had left the Mayadin countryside to begin new operations around Palmyra, their positions in Deir al-Zor now occupied by the Russian-commanded Syrian army’s 5th corps. These Afghan forces have since engaged in sustained fighting with ISIS cells south of Arak and near the Doubayat gas field, which remains under ISIS control. Crisis Group telephone interviews, regime officers, September 2021.Hide Footnote

[In 2021,] the [Damascus] regime and Russia made three major adjustments to their strategy that, taken together, have kept ISIS activity at a low level in 2022 to date.

Alongside these operations, the regime and Russia made three major adjustments to their strategy that, taken together, have kept ISIS activity at a low level in 2022 to date: the convoy policy that ended ISIS strikes on major highways; consistent air support for convoys and units that come under ISIS attack; and the greater number of soldiers deployed in central Syria, which has raised the cost of failure for ISIS cells should they choose to assail fortified positions or waylay patrols.[fn]A regime officer referred to the Badia as “flooded with soldiers now” as compared to 2020. Crisis Group telephone interview, December 2021.Hide Footnote  These adjustments represent a significant evolution. They allowed the regime and its allies to secure the main highways in Deir al-Zor and Hama, capture the Kawm oasis – the town connecting eastern Homs to southern Raqqa – and significantly reduce ISIS attacks in eastern Hama and western Deir al-Zor. The regime slowed the pace of its operations in July 2021, with its forces focusing on solidifying their new positions rather than pushing into the mountains and deserts that remain under ISIS control.

ISIS adjusted to the increased pressure by shifting to a defensive stance, relying on mines, other explosive devices and harassing fire to slow regime patrols and keep them out of the Badia’s remotest parts. Still, in early 2022, ISIS activity remained low in Homs and was nearly non-existent in Hama, two areas where the militants had staged the most attacks in 2020.[fn]A local NDF commander said a Russian bombing campaign in June forced one of two major ISIS cells out of eastern Hama, while the second cell, which had operated around Rahjan for almost a year, left in July after the Syrian army began guarding shepherds and their flocks. Attacks in this governorate resumed in September but remain considerably fewer and less lethal than in 2021. Crisis Group telephone interviews, July 2021 and January 2022.Hide Footnote

Despite these setbacks, ISIS today shows similar capabilities as in 2019, just before its 2020 expansion, and is actively looking to make inroads into regime-held towns. In both late 2019 and late 2021, ISIS cells carried out an average of ten to fifteen attacks on regime forces per month, most of them in rural western Deir al-Zor and eastern Homs, a trend that has continued into 2022.

Yet there are important differences that leave ISIS in a slightly stronger position in 2022. ISIS militants from north-eastern Syria have reportedly been able to use the “reconciliation” that began in Deir al-Zor in November 2021 to infiltrate the local NDF.[fn]NDF members say former ISIS fighters released from SDF camps participated in the “reconciliation” and joined the Deir al-Zor NDF. These men then passed on the locations of NDF weapons caches in SDF-held Deir al-Zor, which had been intended for NDF sleeper cells in attacks on the SDF, to active ISIS cells. ISIS reportedly raided three such caches, seizing around two dozen small arms and several explosive devices. Crisis Group telephone interviews, December 2020. See also Muhammad Hassan, “The regime ‘reconciles’ the people of Deir al-Zor”, Daraj, 14 December 2021 (Arabic).Hide Footnote  Meanwhile, since the end of 2021, at least one ISIS cell has penetrated the southern Homs countryside near the town of Mheen, gradually beginning to conduct operations there. Security forces fear that these cells will attempt to link up with local sympathisers, so as to attack critical infrastructure in Homs, as they did outside Damascus in September 2021.[fn]Crisis Group telephone interview, NDF officer working to establish new militias in Mheen and Qaryatayn, January 2022.Hide Footnote

Thus, 2021 ended with the regime and its allies consolidating the areas they could secure with the newly deployed forces, with a focus on protecting the main highways and gas and oil fields. Meanwhile, ISIS has avoided suffering serious casualties, regrouped in inaccessible areas, and redirected the bulk of its efforts toward Iraq and north-eastern Syria. Yet the group retains experienced cells in central Syria that continue to ambush regime forces at regular, though less frequent, intervals, while also searching for ways to target regime energy infrastructure.[fn]On 17 September 2021, ISIS militants detonated bombs at three locations on the Damascus outskirts, destroying the main pipeline carrying gas to the Deir Ali and Tishreen power plants, as well as two nearby power pylons. In its official claim of responsibility, ISIS framed the attack as part of a new “economic war” on the regime. Crisis Group data gathered by analyst in previous capacity from self-reported regime losses, and ISIS claims, 2021. A NDF officer overseeing anti-ISIS operations in southern and eastern Homs said security forces had reported ISIS cells moving west from the Tiyas area toward Mheen, and that Syrian intelligence suspected the fighters of seeking to connect with ISIS sympathisers living in the southern Homs countryside. Crisis Group telephone interview, January 2022. Since then, local pro-regime Facebook pages have reported three ISIS attacks on regime forces in the Mheen area. See tweet by Gregory Waters, analyst, @GregoryPWaters, 10:58am, 28 January 2022; and another at 2:04pm, 15 February 2022. Mheen marks the edge of the southern Homs suburbs, where several power plants and an oil refinery are located. ISIS may wish to infiltrate this area so as to conduct an attack similar to that in September 2021.Hide Footnote

III. Countering ISIS in the North East

The ISIS insurgency in north-eastern Syria, though still at a low level, is slowly becoming more robust. Operating across the porous lines of control that separate the region from the rest of Syria and from Iraq, the group has turned the north east into the nerve centre of what could become a larger endeavour should a power vacuum arise.

The SDF, which administers most of the north east, has been an indispensable partner in the counter-ISIS coalition. With assistance from U.S. airpower, these Kurdish-led forces had rid Syria of the group’s self-declared caliphate by 2019. The associated Autonomous Administration now controls most former ISIS strongholds east of the Euphrates, spanning the governorates of Hasakeh, Deir al-Zor and Raqqa, as well as Manbij (in Aleppo governorate, west of the Euphrates), and holds thousands of ISIS prisoners. The SDF won (sometimes grudging) recognition from the majority-Arab population for its pragmatism in pursuing the fight. It issued numerous pardons and amnesties to locals who had joined ISIS, willingly or no, and whom it deemed no longer to be a threat. It also refrained from meting out harsh sentences to detained ISIS fighters.[fn]Crisis Group Middle East Report N°204, Squaring the Circles in Syria’s North East, 31 July 2019.Hide Footnote

the Syrian Democratic Forces [are] struggling to forge the sort of lasting trust in predominantly Arab areas that would generate buy-in to its counter-ISIS efforts.

Yet the SDF is struggling to forge the sort of lasting trust in predominantly Arab areas that would generate buy-in to its counter-ISIS efforts. It has largely failed to give the locals, and in particular non-Kurds, meaningful roles in decision-making, while its security measures have been insufficient and often arbitrary. SDF counter-ISIS strategy today relies heavily on raids backed by U.S.-led coalition airpower, during which security forces detain low- to mid-level ISIS fighters.[fn]Crisis Group interviews, members of security forces, Deir al-Zor, May 2021 and March 2022.Hide Footnote  The raids often cause harm to civilians, including wrongful arrests, due to faulty intelligence.[fn]Crisis Group interviews, residents, Deir al-Zor, 2021-2022.Hide Footnote  Popular resentment is growing despite the SDF’s initial successes and ISIS is taking advantage.

A. A Resilient Insurgency

ISIS’s resilience in the north east owes primarily to two factors that hinder the SDF in degrading the group. Perhaps the most important is the lingering fear among the population that the SDF’s control of the area is ephemeral. The second is increasing economic hardship coupled with poor public services. Together, these factors have created openings that ISIS has exploited to undermine civilian trust in the Autonomous Administration.

A. Contested control

The SDF has built its reputation as an effective counter-ISIS force on its ability to hold and secure the areas it captures. Yet this capacity is tied to continued U.S. protection. While few in number, the U.S. troops and air assets based in the area deter the regime and its Russian and Iranian backers from retaking the north east by force. The U.S. deployment also helps keep Türkiye from moving in to crush the SDF, whose parent organisation, the Kurdistan Workers’ Party (PKK), has fought an insurgency in Türkiye since the early 1980s and is designated by Ankara (as well as Brussels and Washington) as a terrorist organisation.

Many residents of the north east worry that this U.S. umbrella may be gone sooner rather than later. U.S. President Donald Trump sharpened the anxiety in 2019, when he responded to Turkish threats to clear the SDF from parts of the north east by announcing an immediate withdrawal of U.S. troops. While he partially walked back that decision soon after, this experience, along with the U.S. withdrawal from Afghanistan, has exacerbated fears that Washington will eventually abandon its Syrian partners.[fn]Crisis Group interviews, SDF commanders and residents, Raqqa and Deir al-Zor, 2022. Following the August 2021 U.S. withdrawal from Afghanistan, many Arab and Kurdish civilians left the north east for Iraq, Türkiye and Europe due to deteriorating economic conditions and fears of imminent U.S. departure. Crisis Group interviews, residents, north-eastern Syria, March 2022.Hide Footnote  Should it do so, many residents believe, it would allow either ISIS and/or the regime and its external backers to return in force.[fn]Crisis Group interviews, residents, Deir al-Zor, 2021-2022; Crisis Group telephone interviews, residents, Raqqa, 2021. A prominent sheep trader and former ISIS prisoner in Raqqa fled to Türkiye with his family in 2021, saying he was convinced U.S. troops would leave soon, giving ISIS free rein to come after him again. Crisis Group telephone interview, Raqqa, March 2021.Hide Footnote  This sense that security may be fleeting discourages the population from cooperating with the SDF’s counter-ISIS raids or providing intelligence on ISIS cells, particularly since ISIS has killed a number of informants – and threatened to kill others – in recent years.[fn]From 2018 to 2021, ISIS stepped up a campaign of assassinations of local leaders and tribal figures, killing more than 200. Omar Abu Layla, “Assassinations increase in Deir Ezzor”, Middle East Center for Reporting and Analysis, 6 March 2021.Hide Footnote

The SDF’s complicated links with the regime compound the problem. Its leadership has maintained a transactional relationship with Damascus throughout the war, staying clear of supporting the Syrian opposition’s calls for regime change. It regularly signals openness to talks with Damascus about a settlement in the north east and, in an attempt to deter Turkish military advances, it signed a deal with Damascus that facilitated a partial Syrian army redeployment to the front in 2019 when the U.S. announced its withdrawal from the area, leaving the SDF facing off against Turkish-backed forces.[fn]Crisis Group Middle East Report N°229, Syria: Shoring Up Raqqa’s Shaky Recovery, 18 November 2021.Hide Footnote  Many residents fear that the SDF is willing to trade away at least some of the districts under its control if the regime will grant a measure of cultural and/or political autonomy to majority-Kurdish areas.[fn]Crisis Group interviews, residents of north-eastern Syria, 2017-2022.Hide Footnote

Senior [Syrian Democratic Forces] figures have attempted to reassure local tribes [that they will remain in control] but considerable mistrust of their intentions in dealing with Damascus endures.

As Crisis Group has previously argued, such a deal seems increasingly far-fetched, at least as long as the U.S. keeps its troops in north-eastern Syria.[fn]Crisis Group Report, Syria: Shoring Up Raqqa’s Shaky Recovery, op. cit.Hide Footnote  Yet the perception that the SDF may pursue this quid pro quo, especially concerning majority-Arab areas, is so strong that many people in the north east hesitate to cooperate with the it for fear of regime retaliation, particularly since the regime describes its return as imminent in its propaganda.[fn]For example, President Bashar al-Assad said, “The Turkish occupier is a U.S. agent in the war, and if it does not leave completely there will be no option but war. … The army’s entry into northern areas is tantamount to the state’s re-entry”. SANA, 31 October 2019 (Arabic).Hide Footnote  Senior SDF figures have attempted to reassure local tribes, especially in the east, but considerable mistrust of their intentions in dealing with Damascus endures.[fn]Crisis Group interviews, civil society representatives and tribal notables, eastern Syria, May 2021.Hide Footnote

From its end, Damascus has stepped up attempts at undermining the SDF’s authority in Raqqa and Deir al-Zor. In November 2021, it opened several “reconciliation” centres in western Deir al-Zor in an attempt both to lure residents of SDF-held areas away from the Autonomous Administration and to make sure that people in regime-held areas remain wary of the SDF.[fn]“Reconciliation” is a process by which the regime pardons Syrians at designated offices once they submit a request to that effect. It is known among Syrians as “settling one’s case with the regime”.Hide Footnote  The reconciliation programs push the narrative that since the regime’s return to the north east is inevitable, trust in the SDF is foolhardy. The regime opened additional centres in regime-held Raqqa the following January and in eastern Aleppo in March.[fn]According to the SDF, over a thousand people from Raqqa and Deir al-Zor pursued individual “reconciliation” agreements with Damascus in late 2021 and early 2022, mostly out of fear that the regime would soon return to the area. Crisis Group interviews, SDF officials, Raqqa and Deir al-Zor, March 2022. Major General Hussam Luka, head of Damascus’ State Security Directorate, and Major General Ali Mahmoud, chief of staff of the elite 4th division, were pictured at the opening ceremonies of most of the “reconciliation” centres, suggesting that the regime organises this process at the highest levels. See tweet by Gregory Waters, analyst, @GregoryPWaters, 4:16pm, 30 March 2022.Hide Footnote

Another major external threat to the SDF’s ability to counter ISIS is its conflict with neighbouring Türkiye. Fighting between Türkiye and the SDF along the Syrian-Turkish border almost certainly would relieve pressure on ISIS; in the meantime, the intermittent clashes since the 2019 Turkish incursion are diverting SDF resources from counter-ISIS raids. Throughout 2021 and into 2022, Ankara continued its multi-pronged campaign against the YPG and PKK, launching drone strikes upon high-profile fighters that at times have accidentally killed civilians, as well as the intended targets.[fn]Amberin Zaman, “Turkish airstrike kills members of US-backed Kurdish force in Syria”, Al-Monitor, 20 August 2021.Hide Footnote  In May, Turkish President Recep Tayyip Erdoğan threatened a renewed offensive against the YPG.[fn]Erdoğan is quoted in a tweet by the Republic of Türkiye’s Directorate of Communications, @Communications, 1:55pm, 23 May 2022.Hide Footnote

Many residents who are frustrated with deteriorating security conditions have accused the YPG of putting its quarrel with Türkiye above the task of clearing ISIS fighters from the north east. A Kurdish internal security commander said, “Our intelligence has been preoccupied with countering Turkey’s cells in the area. This has made us more vulnerable to ISIS”.[fn]Crisis Group interview, Qamishli, March 2022.Hide Footnote  Additionally, Ankara’s threats fuel local scepticism about the sustainability of SDF rule, making it harder for the SDF to gather information.[fn]Crisis Group interviews, Raqqa and Deir al-Zor residents, 2021-2022.Hide Footnote

B. Economic and governance decline

Worsening economic conditions are also contributing to ISIS resilience, along with weaker SDF governance. The SDF’s reputation as a capable service provider took a blow in 2021, as the Syrian lira plunged in value. Shutdowns related to COVID-19 and hyperinflation led to a significant drop in purchasing power and stirred local discontent. Severe water shortages compounded the economic crisis, as the Euphrates reached record-low levels.[fn]The SDF claims that neighbouring Türkiye is deliberately withholding water upstream to destabilise Syria’s north east. But experts contend that drought in Türkiye and global warming are the main reasons for the shortage. See “No Peace for the Dammed: Alarming Water Scarcity in Northeast Syria”, COAR Global, 10 May 2021.Hide Footnote  Agriculture has suffered, including wheat production, which is not only a major source of revenue but also essential to keeping bread affordable.[fn]Crisis Group Report, Syria: Shoring Up Raqqa’s Shaky Recovery, op. cit.Hide Footnote

The area’s economic viability is inseparable from the SDF’s ability to continue its counter-ISIS operations. The SDF has secured some loyalty outside its ranks by employing people: over 200,000 Syrians work for its civilian and military arms, relying on SDF salaries. Patronage is the primary reason – fear of the regime aside – why the transactional alliance between the SDF-held area’s Arab and Kurdish populations has survived as long as it has. Controlling north-eastern Syria’s oil and gas facilities bolstered the SDF’s ability to generate income and pay the running costs of its Autonomous Administration. But reliance on oil sales to a sanctioned and bankrupt regime in Damascus has proven risky. According to U.S. officials, by mid-2021 the regime owed the SDF millions of dollars for oil purchases. The uncollected debt exacerbated the SDF’s budget deficit throughout the year and significantly threatened its ability to continue making payroll.[fn]Crisis Group interviews, U.S. officials, Hasakeh, May 2021.Hide Footnote

Cognisant of this inherent vulnerability, the SDF leadership tried to close deals with foreign companies to extract north-eastern Syria’s oil and sell it abroad.[fn]Calvin Wilder and Kenneth R. Rosen, “Delta Crescent Energy: Refining U.S. Stabilization Strategies in Northeast Syria”, Washington Institute for Near East Policy, 24 November 2021.Hide Footnote  In April 2020, the U.S. Treasury Department granted a sanctions waiver to a U.S. company, Delta Crescent Energy, with the aim of helping the SDF extract and export oil through Iraq. The proposed deal fell through a year later, however, when the Biden administration announced that it would terminate Delta Crescent’s license, leaving the SDF without a ready alternative.[fn]Despite announcing that Delta Crescent would have to cease work in Syria, the Biden administration has quietly granted it several temporary extensions since April 2021. Crisis Group interview, former U.S. official, Washington, October 2021.Hide Footnote  The deal’s controversial legal and political aspects aside, the dilemma is clear: if the SDF’s backers want it to keep the north east stable, they must ensure its financial viability.

Attracting foreign investment in the north east is a challenge. In May, Washington announced a general licence authorising private-sector investment and other activities in non-regime-held areas of north-eastern, as well as parts of north-western Syria. But the licence does not include these areas’ main source of revenue, the oil and gas sectors – not surprisingly, given the contentious politics when U.S. military presence and oil extraction intersect.[fn]Syrian Sanctions Regulations 31 CFR part 542, General License No. 22, Authorizing Activities in Certain Economic Sectors in Non-Regime Held Areas of Northeast and Northwest Syria”, Office of Foreign Assets Control, U.S. Department of the Treasury, 12 May 2022.Hide Footnote  Prospective investors may also be discouraged by pushback from Türkiye, ambiguity surrounding the U.S. military presence or bureaucratic hurdles linked to U.S. and Turkish counter-terrorism sanctions on the PKK.

As a result of the economic plunge, more residents have resorted to smuggling goods and persons into and out of north-eastern Syria.

As a result of the economic plunge, more residents have resorted to smuggling goods and persons into and out of north-eastern Syria. ISIS units have exploited the porous border with Iraq, as well as crossings into areas held by Turkish-supported rebels in the north and by the regime on the Euphrates’ southern and western banks, to transfer money, fighters and even livestock.[fn]Gregory Waters, “Smuggling Away the Future in Syria's Northeast”, Counter Extremism Project, 26 October 2021.Hide Footnote  SDF Commander Mazloum Kobani said, “The informal smuggling routes are a major threat to our economy and our security. We need to crack down on them”.[fn]Crisis Group interview, Hasakeh, 4 March 2022.Hide Footnote  SDF officials blame the Syrian and Iraqi governments for failing to stop the illicit trade, but the SDF itself has found it difficult to suppress smuggling, as contraband is a reliable alternative source of income for many SDF members.[fn]Crisis Group interviews, SDF commanders, Hasakeh, 2021-2022.Hide Footnote

ISIS has also been exploiting worsening economic conditions to enlist new fighters from among the impoverished internally displaced (IDPs). The approximately half-million Syrians who fled to the north east from various parts of the country during the course of the war and are now living in camps provide a recruitment pool for ISIS, which is looking for people to carry out attacks on SDF checkpoints. An SDF official said, “We don’t have the capacity to vet and clear all IDPs. ISIS is able to pay off some young men in the camps to plant IEDs or attack checkpoints in return for a couple of hundred dollars”.[fn]SDF officials contend that most ISIS members in the north east come from other parts of Syria where war has compelled much of the population to flee. They say the fighters easily blend in with all the IDPs living in Deir al-Zor and Raqqa. Crisis Group interviews, Raqqa, May 2021.Hide Footnote

A final shortcoming in SDF governance is the virtual exclusion of Arabs from power, which has alienated a wide stratum of society. Many residents view the SDF’s military, and more so its civil institutions, as nepotistic, with decision-making residing in the hands of Kurds from the YPG or PKK.[fn]For more, see Crisis Group Report, Squaring the Circles in Syria’s North East, op. cit.Hide Footnote  Civilians also see the SDF’s security agencies as compromised, due to the significant number of former ISIS fighters who have joined up.[fn]An SDF commander in Deir al-Zor said the SDF is no longer integrating former ISIS fighters. Crisis Group interview, Deir al-Zor, March 2022.Hide Footnote  The doubts are mutual, as the Kurdish leadership looks askance at intelligence coming from residents whose towns and villages have been major ISIS recruitment hubs and who, for the most part, do not share the SDF’s ideological values and objectives.[fn]Crisis Group interview, SDF official, Hasakeh, May 2020.Hide Footnote  The mistrust is a major impediment to the SDF’s counter-ISIS efforts.

B. ISIS’s Shifting Strategy

ISIS has developed several means of strengthening its insurgency in the north east. The group operates networks of autonomous cells answering to commanders based elsewhere – even outside Syria – making its fighters nearly impossible to uproot. It adjusts its tactics to meet the varying degrees of SDF control from place to place. It keeps a low profile in Raqqa, where the SDF is stronger and where it fears provoking a U.S.-led coalition return, though it still uses the province as a conduit for smuggling of people, goods and weapons. By contrast, it is asserting itself more in Deir al-Zor, where the SDF is already struggling to maintain security.[fn]For more information on SDF weaknesses in Deir al-Zor, see Crisis Group Report, Squaring the Circles in Syria’s North East, op. cit.Hide Footnote

ISIS benefits in many ways from the country’s de facto territorial division among the regime, the SDF and Turkish-aligned groups, which remain locked in mutual hostility. It exploits the holes in the lines of ostensible control to move its fighters and conduct its illicit commerce. It takes advantage of the SDF’s distraction with external foes – chiefly, Ankara and the Syrian rebels it backs – to sabotage its rule from within. Perhaps most dramatically, it undermines the SDF with jailbreaks, the largest of which occurred in January at Ghowayran prison in Hasakeh.

A. An insurgency of cells

Many ISIS cells in north-eastern Syria still operate within the strict command structure of the defunct caliphate, though they retain a degree of autonomy in conducting attacks. ISIS has divided the region into sectors, each with dedicated cells and commanders. According to the SDF, the cells generally consist of two to five fighters using small arms and explosives. The fighters report to a local commander, who in turn reports to an area commander. Cells are intentionally siloed from one another so that arresting members of one cell yields no information about any other. Instances of coordination, such as when two or more cells join in mounting an attack, appear to be directed from the sectoral level.[fn]Crisis Group interviews, SDF and U.S.-led coalition officers, north-eastern Syria, May 2021.Hide Footnote

ISIS fighters reportedly almost always stay close to home base, especially those in Raqqa and the urban belt in the Middle Euphrates Valley. Cells operating in rural areas, such as Kabash and Hazima in northern Raqqa province, or in Shaddadi in southern Hasakeh, are more mobile. Cells consist of a mix of locals – particularly in Deir al-Zor – and IDPs – particularly in Raqqa – with IDPs making up an increasingly large portion of militants.[fn]Crisis Group interviews, SDF and security police officials, north-eastern Syria, May 2021 and March 2022.Hide Footnote  Security officials believe many of these cells are based in the desert along the boundaries of Raqqa, Hasakeh and Deir al-Zor governorates, whence they move south to conduct attacks. They also think that cell and sector commanders live outside the areas where insurgents are most active.[fn]SDF and YPG security police commanders in Raqqa and Deir al-Zor routinely claim that ISIS commanders are based in Iraq, northern Aleppo, Idlib or the Badia. Crisis Group interviews, Raqqa and Deir al-Zor, May 2021 and March 2022.Hide Footnote

Most counter-ISIS operations round up only low-level insurgents, who can be replaced by new fighters recruited in the north east and trained in the Badia.

The porous lines of control separating various parts of Syria make it difficult for security forces to degrade the insurgency in the north east – and the fact that commanders live elsewhere makes it even more so. ISIS units can escape pressure in one area by moving elsewhere. Plus, most counter-ISIS operations round up only low-level insurgents, who can be replaced by new fighters recruited in the north east and trained in the Badia. The lines of control separating the north east from the centre have always been permeable, but as described above, ISIS has been crossing with greater ease since 2020, when it expanded in central Syria. Meanwhile, the security forces struggle even to identify the commanders, let alone arrest them, due in large part to the difficulties the SDF and U.S.-led coalition face in building effective intelligence networks.

Iraq also serves as a source of men and supplies for ISIS, with the group taking advantage of pre-existing links to smuggling networks in Iraq’s Ninewa and Anbar governorates, as well as in Deir al-Zor and Hasakeh. Some SDF commanders believe that the Shaddadi countryside, situated on the boundary of Deir al-Zor and Hasakeh governorates, serves as a storehouse for ISIS, where it keeps supplies and weapons it brings in from Iraq before distributing them in Deir al-Zor, Raqqa and the Badia.

An IDP camp on the southern side of Raqqa city, Syria. May 2021. CRISIS GROUP / Gregory Waters

B. A regional division of labour

As part of its strategy in the north east, ISIS appears to assign different functions to the various areas where it operates in the north east. Somewhat counter-intuitively, the group did not step up its activities in Raqqa when the U.S.-led coalition withdrew its forces from the governorate in late 2019. The SDF, the U.S. military and other close observers suspect that ISIS is purposely lying low in Raqqa so as not to draw coalition forces back into the area.[fn]Crisis Group interviews, SDF officials, U.S. military personnel and other close observers, Raqqa, May 2021. ISIS media similarly underreport operations in central Syria, taking credit for far fewer attacks than its cells are carrying out. See Waters and Winters, “Islamic State Under-Reporting in Central Syria: Misdirection, Misinformation or Miscommunication?”, op. cit. ISIS apparently did the same in Hasakeh prior to the January prison raid. The weapons caches and safehouses in neighbourhoods around the prison, the number of fighters involved and the use of two suicide car bombs all suggest a much deeper level of ISIS infiltration in the city than the number of previous attacks there would. The SDF likely had a false sense of security. Crisis Group interview, SDF security police commander, Qamishli, March 2022.Hide Footnote  Both SDF intelligence officers and Raqqa internal security commanders said ISIS has only about ten fighters active in each of the five sectors that make up Raqqa city, but that more sleeper cells may exist.[fn]Crisis Group interviews, SDF intelligence officers and Raqqa security police commanders, Raqqa, May 2021.Hide Footnote  They believe that many more ISIS fighters are lurking in the Raqqa countryside than the number of attacks would suggest, though the cells’ inactivity makes it hard to know for sure.

Yet Raqqa appears to be central to logistics and financing for ISIS in the north east.[fn]Crisis Group interview, SDF commander, Hasakeh, March 2022.Hide Footnote  According to regime and SDF security sources, ISIS uses Raqqa as a corridor for transporting fighters and supplies to and from its various insurgent theatres. It brings veteran fighters, but especially new recruits, into the city via smuggling routes. Once they arrive near the regime-SDF line of control, the recruits blend in by posing as civilians and wait until they can head for the training camps in the Badia’s vast desert and mountains.[fn]Crisis Group interviews, members of Raqqa city security forces, Raqqa, May 2021.Hide Footnote  SDF and U.S.-led coalition officials indicated that such movements became common after U.S. troops withdrew from Raqqa in late 2019.[fn]Crisis Group interviews, SDF officials, U.S. military personnel and other close observers, Raqqa, May 2021.Hide Footnote

In Deir al-Zor [ISIS] regularly kills civilians. … creating an atmosphere of fear.

ISIS cells in Deir al-Zor, on the other hand, are overtly disrupting the SDF’s efforts to exercise its writ. Unlike in Raqqa, where militants mostly attack soldiers, in Deir al-Zor they regularly kill civilians, whether coalition informants or tribal sheikhs believed to be working with the SDF. In Ramadan of 2022, for example, ISIS fighters killed seven local council employees and wounded four more in an assault on the council public relations office chairman’s house while he was hosting an iftar dinner.[fn]April Sleeper Cell Report: Bloodiest Month Yet Due To ISIS Ramadan Campaign”, Rojava Information Center, 8 May 2022.Hide Footnote  Such killings have been common since ISIS lost its territory in 2019, and with them it has succeeded in creating an atmosphere of fear, hindering the authorities’ attempts to gather intelligence and integrate local leaders into governing bodies.[fn]Crisis Group interviews, security commanders, Deir al-Zor, March 2021.Hide Footnote

Despite regular arrests and killings of ISIS fighters, security in Deir al-Zor in 2021 and 2022 was the same or worse than in 2020.[fn]Crisis Group interviews, SDF commanders, Deir al-Zor, 2021 and 2022.Hide Footnote  The reason seems to be that ISIS fighters can easily cross the line of control along the Euphrates that separates the governorate’s SDF- and regime-held parts. The cells have long taken advantage of incompetence and corruption among forces on both sides of the river to move men and supplies back and forth as needed.[fn]Crisis Group interviews and telephone interviews, SDF and NDF commanders, north-eastern Syria, 2021-2022.Hide Footnote  When fighters come under pressure in eastern Deir al-Zor, they can slink away to the Badia, and when they are needed east of the Euphrates, they can be spirited over from the west. A local SDF commander in Deir al-Zor said smuggling across the river has increased since 2021 due to economic woes, adding that the SDF feels powerless to stop it. He said most of the smuggling occurs along a 125km stretch between Jdeid Aigadat, south of Deir al-Zor, and Baghouz on the Iraqi border.[fn]Crisis Group interview, Deir al-Zor, March 2022.Hide Footnote

The smuggling routes are a double-edged sword. Both the regime and the SDF benefit economically from the illicit trade going from Raqqa to Idlib and northern Aleppo via Manbij, and from Iraq to both the regime- and SDF-held parts of Syria.[fn]A regime soldier from Idlib deployed in the Badia said it costs about $1,000 to smuggle someone from Idlib to Raqqa and then into the desert. Crisis Group telephone interview, September 2021.Hide Footnote  Meanwhile, security officials in Raqqa say, ISIS uses these routes to reinforce cells in the city and countryside with fighters from the Badia when the SDF kills or detains their members.[fn]Crisis Group interviews, Raqqa, May 2021.Hide Footnote

C. A diversity of income

The north east has become a pillar of ISIS finances. The SDF-held territory is rich in natural resources, including oil and gas, and has longstanding economic links to other parts of Syria, as well as Iraq. ISIS relies on three primary funding sources: racketeering, taxation and smuggling. With this money ISIS buys weapons and supplies, offers stipends to its members’ families, bribes SDF guards to secure detainees’ release, recruits new fighters and pays the occasional hit man.[fn]Crisis Group telephone interviews, north-eastern Syria residents, 2021-2022.Hide Footnote

In many ways, ISIS operates like a mafia, preying on governing institutions and businesses through extortion and blackmail. In some cases, it has recruited local council employees to collect protection money from their colleagues. It also shakes down traders, artisanal oil refinery owners, bakers and smugglers. It is unclear how ISIS determines the amount of money to demand from each target, but SDF officials claim that oil investors and refinery owners pay thousands of dollars per month to avoid ISIS attacks on their businesses.[fn]Crisis Group interviews, north-eastern Syria, May 2021.Hide Footnote

ISIS sympathisers send messages to wealthy residents demanding zakat [the Islamic alms that ISIS has levied as a tax in various places].

Another source of income is zakat, the Islamic alms that ISIS has levied as a tax in various places. This practice is evident in Deir al-Zor, in particular, but in Raqqa as well.[fn]An SDF commander claimed that ISIS fighters blew up a shopping center in Raqqa earlier this year when its owner refused to pay them. Crisis Group interview, Raqqa, March 2022.Hide Footnote  ISIS sympathisers send messages to wealthy residents demanding zakat, telling them where to deposit the money.[fn]Crisis Group interviews, local traders, al-Busayra, Deir al-Zor, October 2021.Hide Footnote  SDF officials and many local people believe that it is often not militants but criminals posing as ISIS fighters who are scaring their targets into paying with these notes, though, in reality, some ISIS activity is nearly indistinguishable from banditry.[fn]Crisis Group telephone interviews, security officials and residents, Raqqa and Deir al-Zor, January-June 2022.Hide Footnote  Regardless, security forces have been unable to end this practice, and people pay, having no faith in the SDF’s ability to find the culprits. A well-known merchant in Deir al-Zor said, “No one will be able to protect me from them, so even if they are not ISIS, I won’t risk myself and my family for a few hundred dollars [yearly]”.[fn]Crisis Group interview, Deir al-Zor, October 2021. Local merchants said the amounts ranged from $500 to $3,000, or roughly 2.5 per cent of each person’s estimated yearly revenue. Crisis Group interviews, Deir al-Zor, October 2021.Hide Footnote

Lastly, there is smuggling. ISIS exploits the networks that connect the north east to both rebel- and regime-controlled areas, as well as to Iraq, increasing its reliance on them throughout 2021.[fn]The Turkish military presence in a pocket of north east Syria since October 2019, which introduced a new internal border, could help explain the increase in ISIS smuggling activities in 2021. U.S. and SDF officers claim that this area, which stretches from Tel Abyad to Ras al-Ain, has been the weak point in their counter-ISIS efforts. They allege that Turkish-backed factions operating, being corrupt and fragmented, have allowed the area to become a conduit for ISIS elements. Crisis Group interviews, Hasakeh, May 2021. Smuggling has also increased between north-eastern Syria and both central Syria and Iraq, with SDF commanders blaming the declining economy for growing corruption and local participation in illicit activities, on which ISIS is able to capitalise. Crisis Group interview, Hasakeh, March 2022.Hide Footnote  ISIS members based in the north east rely on funds transferred from abroad.[fn]Most of these transfers happen not through banks but through the informal hawala system. The person sending the money gives cash to a trusted middleman, usually a merchant, who records the amount and calls a colleague in the place where the intended recipient lives. This person, usually also a shop-owner of some kind, record the amount and pays it in cash to the recipient. The merchants then settle the accounts between themselves in money, goods and services.Hide Footnote  In May 2022, the U.S. Treasury sanctioned five individuals who “played a key role in facilitating the travel of extremists to Syria and other areas where ISIS operates … [and] also conducted financial transfers to support ISIS efforts in Syria-based displaced persons camps by collecting funds in Indonesia and Turkey, some of which were used to pay for smuggling children out of the camps and delivering them to ISIS foreign fighters as potential recruits”.[fn]Treasury Designates Facilitation Network Supporting ISIS Members in Syria”, U.S. Department of the Treasury, 9 May 2022.Hide Footnote  Three of the sanctioned individuals were women, highlighting the role pro-ISIS women detained in al-Hol camp have played in conducting attacks on other residents, recruiting new members and moving funds.[fn]John Saleh, “The Women of ISIS and the Al-Hol Camp”, Washington Institute for Near East Policy, 2 August 2021.Hide Footnote

D. A lack of strong institutions

A key part of ISIS’s strategy in the north east is to weaken the SDF as a governing entity and service provider. In 2019 and 2020, ISIS cells focused on strong-arming public-sector employees into resigning, as a way to disrupt essential service provision and thus tarnish the SDF’s image, particularly in Arab-majority areas of Raqqa and Deir al-Zor.[fn]On several occasions, local council employees received text messages instructing them to go to a local mosque, where ISIS fighters told them to “repent” of their sins. ISIS targets the “repentant” people for death if they return to their jobs. There have been numerous other incidents of intimidation. In February 2021, nine Deir al-Zor central canton administration members resigned from their positions in the face of ISIS threats. Crisis Group telephone interviews, residents, Deir al-Zor, November 2021.Hide Footnote  In other cases, ISIS instructed “repenting” employees to stay in their positions so as to feed the insurgency inside information.[fn]Crisis Group interviews, residents, Deir al-Zor, 2021-2022.Hide Footnote  The group seems to be using this tactic less often of late, however.

ISIS has occasionally targeted big infrastructure projects or essential services, and, more frequently, bakeries run by the Autonomous Administration; it also tried and failed to attack a Raqqa water station.[fn]Crisis Group interviews, security officers, Raqqa, March 2022.Hide Footnote  But it has claimed only one of the few attacks on infrastructure projects that have occurred since mid-2020. SDF commanders say ISIS realised it would be unable to fill the vacuum if local institutions were to collapse entirely.[fn]Crisis Group interviews, security officers, Raqqa, March 2022.Hide Footnote Others believe that ISIS wants to avoid causing an institutional breakdown that would draw the U.S.-led coalition back in, or that it simply lacks the capacity to conduct complex attacks and is choosing easier targets like checkpoints instead.[fn]Crisis Group interviews, internal security officers and U.S officials, Raqqa, May 2021.Hide Footnote

From mid-2020 onward, ISIS intensified its attacks on checkpoints in the countryside, using explosive devices to target military vehicles and recent SDF recruits in an apparent attempt to deter others from cooperating with security forces. It has used cells of five or six assailants, with several more fighters keeping watch nearby.[fn]Crisis Group interviews, SDF and internal security officials, Raqqa and Deir al-Zor, May 2021.Hide Footnote   With such attacks, ISIS has hindered its ability to gather reliable intelligence. The SDF has long struggled to find trustworthy interlocutors in Deir al-Zor, where the Kurdish-dominated group lacks local knowledge and the large numbers of internally displaced weaken the ability of local notables to act as brokers.[fn]For more, see Crisis Group Report, Squaring the Circles in Syria’s North East, op. cit.Hide Footnote  Defective intelligence gathering caused the SDF to often act on misinformation, arresting innocent people.[fn]  Such blunders have given ISIS additional leeway in its operations.[fn]Crisis Group telephone interviews, residents, Deir al-Zor, 2021-2022.Hide Footnote

ISIS … constantly threatens the [Syrian Democratic Forces] rank and file, causing a general fear among the population about joining [them] and Autonomous Administration institutions.

ISIS also constantly threatens the SDF rank and file, causing a general fear among the population about joining SDF and Autonomous Administration institutions. For example, the frequent targeting of the SDF’s internal security forces has made residents reluctant to enlist. As a result, and though SDF-controlled Deir al-Zor covers a large swathe of territory, the number of security personnel there is low, at 4,500.[fn]Crisis Group interview, internal security forces commander, Qamishli, March 2022.Hide Footnote  ISIS may not be able to replace the SDF as service and security provider, but it can make the SDF look bad.

Finally, ISIS poses a significant threat to travel within and access to particular regions in the north east, further hindering service provision. It has, for example, mounted frequent assaults along the Khorafi road, the main artery connecting Hasakeh to Deir al-Zor.[fn]The highway is of strategic importance to Deir al-Zor as the main road connecting this remote governorate to Hasakeh, the closest place where many important services, including medical treatment, are available.Hide Footnote  The highway, more than 100km long, cuts through a wide-open desert that ISIS militants have used as both refuge and staging ground. Since 2020, attacks on checkpoints and drive-by shootings have led the internal security forces to stay off the road for fear of becoming ISIS targets.[fn]Crisis Group interview, SDF commander, Hasakeh, May 2021.Hide Footnote

In 2021, the same situation prevailed on the highway connecting Hasakeh with Raqqa, where the SDF repeatedly had to remove outposts temporarily, saying it could not protect them from ISIS attacks. Security on the Raqqa road improved significantly in 2022, however, after the SDF refurbished the highway, set up more than a dozen checkpoints and began sending out regular patrols in the surrounding area.[fn]Crisis Group interviews, internal security forces commanders, Raqqa, March 2022; and Crisis Group observations during travel on the highway, May 2021 and March 2022.Hide Footnote

The diminishing security presence on the roads throughout 2021 heightened travellers’ threat perception and soured them on the SDF. While the SDF was able to reinforce its outposts on the Qamishli-Raqqa highway in early 2022, the Khorafi road still had only three minor checkpoints as of March.[fn]Crisis Group interview, SDF commander, Hasakeh, March 2022; and Crisis Group observations during travel on the highway, May 2021 and March 2022.Hide Footnote  The security forces are scarcely able to monitor the plains between Hasakeh city and Deir al-Zor for ISIS cells. Aid organisations find it difficult to deliver services, and many NGO workers are reluctant to visit Deir al-Zor at all. Anti-SDF sentiments are rising among Deir al-Zor residents, who accuse the SDF of doing too little to secure the area.

A regime soldier stands guard outside the regime security box in Qamishli, Syria. May 2021. CRISIS GROUP / Gregory Waters

E. A prison attack

Jailbreaks are an integral part of ISIS’s strategy and a recurring theme in its online messaging.[fn]In early 2021, ISIS’s online magazine al-Naba released an infographic entitled, “We have not forgotten you”, outlining its numerous attempts to free its detained comrades.Hide Footnote  For years, both SDF and U.S. officials have raised concerns about security in the 27 SDF-run prisons, which hold an estimated 10,000 Syrian and foreign ISIS fighters, as well as in two detention camps and two child rehabilitation centres, which hold over 60,000 people, including wives (or widows) and children of ISIS fighters.[fn]SDF commanders said there are around 27 detention facilities holding ISIS inmates. Crisis Group interviews, Hasakeh, March 2022. A U.S. government source said there are only fourteen. “Operation Inherent Resolve – Lead Inspector General Reports to the United States Congress, 1 July-30 September 2020”, 30 September 2020.Hide Footnote  Many of the buildings are converted schools, hospitals or warehouses, and were not meant to hold prisoners indefinitely. The SDF is concerned that ISIS could engineer mass escapes from these facilities by assailing them from the outside, encouraging prisoners to riot or doing both at once. Inmates have made several unsuccessful escape attempts in recent years, and in November 2021, the SDF foiled an ISIS plot to attack the Ghowayran prison in Hasakeh.[fn]SDF commander Kobani said the SDF had underestimated ISIS after foiling its past attacks. Crisis Group interview, Hasakeh, March 2022.Hide Footnote

The 20 January 2022 ISIS attack on the same prison was a reminder that these makeshift facilities are a glaring security vulnerability.[fn]See Louisa Loveluck and Sarah Cahlan, “Prison break: ISIS fighters launched a brazen attack to free their comrades”, Washington Post, 3 February 2022.Hide Footnote  It was the group’s first major assault on an SDF prison holding both Syrian and foreign fighters, along with minors. The SDF claims that around 50 ISIS militants carried out the attack, detonating a car bomb at the prison gate and another close to the wall. ISIS cells had set up weapon caches nearby and coordinated the explosion’s timing with inmates who staged a riot as the bomb went off, overpowered the guards and broke out of their cells. Within a few hours, scores of ISIS militants had escaped into adjacent neighbourhoods. Simultaneously, ISIS cells in Raqqa and Deir al-Zor blocked roads and fired upon checkpoints, warning residents not to approach SDF headquarters.[fn]Following the jailbreak, ISIS conducted a string of attacks on SDF positions and military vehicles in eastern Deir al-Zor governorate. On 9 February, for example, militants attacked an SDF base at the al-Milaj water station on the outskirts of al-Jazra. The following day, a sleeper cell attacked an SDF checkpoint in the village of al-Shaheel in Deir al-Zor, executing five SDF members and seizing their weapons and ammunition. On 14 February, ISIS claimed an attack conducted by unidentified gunmen on a motorbike, who opened fire on a SDF vehicle on the main road connecting the towns of al-Busaira and al-Atal, killing three SDF fighters. On 15 February, ISIS militants attacked a water station used by the SDF as a military base in the town of al-Zir. ISIS subsequently raided an SDF checkpoint in al-Shehel town on the same day. ISIS attacks in western Deir al-Zor also continued, albeit on a smaller scale than in the governorate’s eastern part. On 12 February, unidentified gunmen carried out an attack on SDF headquarters in Hamar al-Ali village in Deir al-Zor’s western countryside, causing limited material damage and no human casualties. On 17 February, an ISIS cell conducted a drive-by shooting on an SDF position in the town of al-Nimleyeh in northern Deir al-Zor, wounding a SDF fighter. Crisis Group interviews, SDF security commanders, Deir al-Zor, March 2022.Hide Footnote  ISIS held some 700 boys hostage during the siege, injuring dozens of them.[fn]Crisis Group interview, UN official, May 2022.Hide Footnote

[ISIS’s] attack [on Ghowayran prison] showcased the shortcomings of existing security mechanisms.

The attack showcased the shortcomings of existing security mechanisms. A prison holding thousands of ISIS fighters was guarded by members of unarmed self-defence units who had received minimal training before being deployed.[fn]All SDF prisons are guarded by a self-defence force made up of volunteers, who got only about 45 days of training and who were almost exclusively equipped with non-lethal weapons so that prisoners would not be able to seize firearms during a riot.Hide Footnote  The inmates quickly overran this under-trained and under-equipped force. ISIS killed 65 of them and took 20 others captive. According to the SDF, the inmates had previously paid guards to bring in smart phones, which they then used to communicate with ISIS cells outside. The fact that the attackers were able to drive through several SDF checkpoints with cars laden with explosives and reach the prison reveals the security weaknesses in the area.[fn]During a visit in March 2022, Crisis Group saw no changes in external prison security, such as checkpoints or physical barriers, that would prevent access to the main gate. The gate lies on a busy road that remains open in both directions, even though the rigged cars used it to approach the prison.Hide Footnote

The ensuing battles between the SDF and ISIS lasted more than two weeks and left over 200 SDF fighters dead.[fn]Crisis Group interview, security commander, Qamishli, March 2021.Hide Footnote  The attack also revealed serious problems with the SDF’s ability to coordinate its various security forces and highlighted how deeply ISIS had infiltrated local security forces in the north east.[fn]An SDF security police commander in Hasakeh said he faced difficulty coordinating between the different security branches both in the lead-up to and the response after the attack. He claimed that security in Hasakeh had become lax in previous months, saying, “Before the attack, we worked on the assumption that we had eradicated their threat. We did not imagine that they could take over a prison in one night. But since the attack, we have changed our strategy in Hasakeh and Shaddadi to focus more on ISIS”. He said the SDF’s elite counter-terror force, which receives training directly from the U.S.-led coalition, has been deployed around some of the prisons though the overall administration of prisons remains in the hands of the volunteer force. Crisis Group interview, Qamishli, March 2022.Hide Footnote  Hundreds of ISIS prisoners, including some commanders, escaped before some of them were captured or killed.[fn]A terrorism expert at a multilateral organisation said an initial assessment suggested that 800 ISIS prisoners were missing after the attack. Crisis Group telephone interview, February 2022. The SDF claimed to have killed nearly 400 “ISIS fighters”, almost all of whom were prisoners, leaving around 400 prisoners unaccounted for. SDF officers in Deir al-Zor said around 30 escaped prisoners arrived in the town of Dhiban shortly after the attack, crossing into the regime-held part of Deir al-Zor. Crisis Group interviews, March 2022. An internal security commander said several ISIS leaders may have escaped, and that the SDF does not know how many prisoners fled, as it did not know how many detainees the jail housed in the first place. Crisis Group interview, Hasakeh, March 2022.Hide Footnote

Equally vulnerable are SDF camps holding women and children. In the first quarter of 2022, unidentified militants committed more than fifteen murders in al-Hol camp.[fn]Crisis Group interview, Qamishli, March 2022. See also “April Sleeper Cell Report: Bloodiest Month Yet Due to ISIS Ramadan Campaign”, op. cit.Hide Footnote  Humanitarian workers seeking to provide medical services in al-Hol and UN officials monitoring conditions there note with alarm that violence is surging. The hardline women still loyal to and affiliated with ISIS are increasingly emboldened, targeting detainees for “deviant” behaviour, as well as camp guards. Weapons appear to make their way into the camp easily, despite supposed restrictions. Meanwhile, many camp residents are able to buy their way out of the camp and often out of Syria. Humanitarian organisations report that women in al-Hol continue to have babies, suggesting visits by men.[fn]Crisis Group interviews, UN officials and humanitarian workers, May 2022.Hide Footnote  SDF Commander Mazloum Kobani said, “Al-Hol is our ticking time bomb. If we couldn’t even secure the relatively small Ghowayran prison, how can we control al-Hol with our current resources?”[fn]Crisis Group interview, Hasakeh, March 2022.Hide Footnote

IV. Looking Ahead

ISIS has taken advantage of war, chaos and the state’s lack of legitimacy to expand its operations and territorial presence in Syria. Counter-ISIS gains have been significant but remain contingent on preserving the delicate calm that has allowed all parties to focus on countering the group instead of fighting one another. The violence that followed the October 2019 Turkish incursion into north-eastern Syria abated once Ankara agreed to a negotiated ceasefire. Any new escalation between the SDF and Türkiye or Turkish-aligned groups would give ISIS additional breathing space.

By the same token, the Syrian regime and its allies were only able to roll back ISIS’s significant gains in central Syria after Ankara and Moscow had negotiated a ceasefire in Idlib. There is a clear need for the U.S., Türkiye and Russia to weigh in with their respective Syrian partners to abide by these agreements and avoid skirmishes that could trigger an escalatory cycle of violence that ISIS could exploit. They should work to prevent the Ukraine war from spilling over into Syria or undermining existing ceasefires and deconfliction mechanisms.

The U.S. presence in Syria … has been crucial in keeping the lid on a possible ISIS resurgence.

The U.S. presence in Syria, though light in footprint, has been crucial in keeping the lid on a possible ISIS resurgence, not only in the north east, but in other parts of Syria where the U.S. continues to conduct air raids against top ISIS leaders. While many residents suspect the U.S. will soon depart, and thus feel uncomfortable helping the SDF fight ISIS, the residual coalition presence in eastern Syria remains the driving force behind counter-ISIS operations – because it both deters further military moves on the area and gives the SDF the support it needs to continue battling militants. Meanwhile, the SDF’s leadership of those operations has allowed the U.S. to avoid both heavy deployment and significant losses. It has also prevented Washington from getting dragged into micro-managing governance in areas captured from ISIS.

Yet twenty years of the global “war on terror” have shown that military action alone does not suffice to counter insurgencies effectively. Preventing ISIS from resurging will require political and economic investment from the U.S.-led coalition in the north east. Growing local grievances as a result of deteriorating economic conditions and the SDF’s shortcomings are eating away at the group’s credibility as a stabilising force and governing body in these areas.

The coalition should therefore increase its funding for restoring public services, thus helping the population to maintain their livelihoods amid the economic crisis. They should place particular emphasis on economic aid to the rural areas of Raqqa and Deir al-Zor, where most people rely on agriculture — which war and climate change have damaged severely — for income. They should condition their support for the SDF on internal reforms that would give local technocrats a meaningful role in managing security and the economy. Such reforms would improve performance of both sectors while giving a broader cross-section of elites a bigger stake in the area’s future.

An answer is also needed to the challenge posed by the SDF’s make-shift facilities holding ISIS fighters and their families. The January jailbreak made clear the risks inherent in relying on the SDF to detain the prisoners indefinitely. The U.S.-led coalition should support the SDF in slowly reducing the number of prisoners, while at the same time constructing new, purpose-built jails and offering technical and financial assistance to the SDF in prosecuting Syrian ISIS members. Priority should be given to assisting the SDF in taking an accurate census of how many militants it holds and which ones used to serve in leadership roles. Creating such a database will help the SDF and coalition direct funds to prevent future prison breaks. Meanwhile, the SDF should allocate more resources to its internal security forces, especially in Deir al-Zor, and better coordinate its various security forces while letting more Arab commanders help make decisions about these reforms.

Finally, countries need to accept responsibility for their nationals detained or interned in Syria for their alleged involvement with ISIS. While they should first repatriate the thousands of children who have been stranded in tents for over five years, they need to bring home all their nationals, regardless of age or status, eventually.

Donors should also consider allocating resources to support the rehabilitation and reintegration of ISIS-linked Syrian families. The SDF has already released hundreds of people in desperate need of psychological, educational and vocational support. The SDF’s inability to care for these deeply traumatised women and children places the burden on their communities of origin. The families often encounter hostility when they go home, however, partly because people resent their ISIS affiliation and partly because people are consumed with survival after years of war and a collapsing economy. The communities of origin often lack the capacity to cope with ISIS-linked youth, in particular. It should not be left to residents of the ISIS families’ hometowns, many of whom suffered grievously under ISIS rule, to lead reintegration efforts.

The most important task is to sever the links between ISIS cells in central Syria and the north east.

While the adjustments above would greatly enhance the U.S.-led coalition’s counter-ISIS mission, the most important task is to sever the links between ISIS cells in central Syria and the north east. Securing the line of control along the Euphrates and increasing surveillance of informal crossings would go a long way toward improving the coalition’s efficiency and help stabilise Deir al-Zor. The same applies to the Syrian side of the SDF-controlled parts of the Syrian-Iraqi border in Hasakeh and Deir al-Zor. Those who profit from smuggling across these lines, including SDF (and often PKK) members, will resist a clampdown, but the SDF leadership and coalition can no longer ignore the threat the illicit commerce poses.

On the river’s west bank, the Syrian regime and its Russian and Iranian allies made significant progress in 2021 in blunting the ISIS expansion in central Syria. But these advances should not be taken for granted. If the regime’s grip loosens, ISIS may very well rebound in these areas, for instance if Russia were to redeploy military assets from Syria to Ukraine, or if the regime were to launch a new offensive in Idlib. Pushing ISIS deep into the Badia or across the Euphrates to the east has been a winning strategy thus far, and Damascus likely does not mind ISIS destabilising SDF-controlled areas and causing trouble for the U.S.-led coalition. But for the regime and its backers, the group’s growing strength in the north east could easily become their problem, too. Just like the SDF, the regime needs to rein in those inside its security apparatus who facilitate smuggling.

The most efficient way for the various actors fighting ISIS to cut the ties between the central and north-eastern theatres would be to share information with one another, perhaps via the establishment of compartmentalised intelligence cooperation cells dedicated to the counter-ISIS effort. Yet they are unlikely to do so, due to lack of trust and political obstacles. There may be potential for improvement along the Iraqi border, but inside Syria, antagonism – between the SDF and the regime in the south, between the SDF and in the Turkish-aligned groups north and increasingly also between the U.S. and Russia – will most likely prevent even the most basic coordination.

But as long as all involved actors would rather fight one another than ISIS, the militants will continue to thrive in the shadows of their mutual distrust and harm the interests of all. ISIS has long profited – even in its heyday – from divisions among its rivals. When conditions are ripe, it may well re-emerge into broad daylight and the lives, energy and money expended on uprooting it will have been wasted.

V. Conclusion

The years following ISIS’s territorial defeat have seen the group maintain a resilient insurgency throughout central and north-eastern Syria. Campaigns waged by the Syrian regime and SDF that aimed more to achieve military victory than to forge political or economic stability have left the door open for ISIS cells to survive and sometimes flourish.

In its rush to beat the SDF to the Euphrates in 2017, the regime failed to clear ISIS remnants from the Badia. These cells endured, gradually regaining strength and establishing camps to train a new generation of fighters, who now imperil regime transit routes and energy infrastructure. In the north east, ISIS cells have capitalised on local grievances over shortcomings in the SDF’s governance and service provision. The threat of renewed Turkish offensives has prevented the cash-strapped SDF from doing more to stabilise the area. Meanwhile, continued hostilities between the SDF and the regime, corruption in security forces and deteriorating economic conditions have fostered smuggling that ISIS cells have exploited to move men and supplies from region to region.

These factors have enabled ISIS to run extensive financial operations in the north east and escalate attacks at will. The hostility among ISIS’s enemies to which the group primarily owes its survival appears unlikely to calm any time soon, giving it breathing space and increasing chances it will rebound. Its renewed ability to move explosives-laden vehicles throughout the north east means that even hardened outposts are not safe from attack. Detention facilities holding ISIS fighters and their families remain highly vulnerable. The Hasakeh jailbreak in January should serve as a wake-up call to all sides engaged in counter-ISIS efforts. All should work to disrupt the outreach and finance campaigns that have bolstered the ISIS ranks in central and north-eastern Syria – and to avert new conflicts among themselves at all costs. ISIS may have lost its caliphate, but it is far from vanquished.

Deir al-Zor/Hasakeh/Washington/Brussels, 18 July 2022

Appendix A

Map of Central and Northeast Syria, June 2022. Borders, roads, and water from Humanitarian Data Exchange (HDX); control areas adapted from @Suriyakmaps; oil, gas and infrastructure from Crisis Group database.

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