The White House announced that following the withdrawal of U.S. forces, "a small peacekeeping group of about 200 will remain in Syria for a period of time". However, the following day media reports clarified that the figure may actually be 400. 

President Rouhani met with his Turkish and Russian counterparts for discussions on Syria. In a press conference, he suggested that "if the U.S. retreats its forces from Syria, based on our intelligence we know that they will continue to meddle in Syria". Rouhani also posited that "illegal interference in Syria by the Zionist regime [i.e. Israel] is a source of concern for the people of this country and other nations in the region. [The] Israelis bomb anywhere in the region and fly on Lebanese and Syrian soil whenever they wish, and unfortunately, the UN and global authorities are silent about these continued acts of aggression in Syria". 

Secretary Pompeo, in Warsaw for the Ministerial to Promote a Future of Peace and Security in the Middle East, described the proceedings as "absolutely historic... the first time in a quarter of a century that you had the prime minister of Israel in the same room talking about threats in the Middle East with senior Arab leaders from all across the Middle East". "This gathering is certainly about Middle East peace and stability," he explained. "You can't talk about that without talking about the threat from the Islamic Republic of Iran, whether it's Hizbollah, Hamas, the Houthis - I call them the three H's - whether it's their work against the Iraqi government... whether it's what they're doing in Syria today". Pompeo also remarked that "we don't expect the Iranian people to support the U.S. We expect them to take care of their own country... we want the Iranian people to have the opportunity to live in a prosperous, peaceful society and one that is controlled by their desires, their wishes. And if we can get that, I am very confident that these behaviours that we see in Iran will change dramatically". On Yemen, Pompeo stressed that "we have two problems - three problems really. The first problem is al-Qaeda... the second problem is Iran continuing to fund the Huthis... it provides missiles to the Huthis that they launch into airports in Saudi Arabia and the Emirates". 

In remarks to a ministerial meeting of the counter-ISIS coalition, President Trump indicated that "the U.S. military, our Coalition partners and the Syrian Democratic Forces have liberated virtually all of the territory previously held by ISIS in Syria and Iraq. It should be formally announced sometime probably next week that we will have 100 per cent of the caliphate". He went on to state that "as countries in the region and across our Coalition step up their commitments, as we continue to destroy the remnants - that's all they have, remnants. But remnants can be very dangerous". 

In remarks to a ministerial meeting of the counter-ISIS coalition, Secretary Pompeo maintained that "the drawdown of [U.S.] troops [from Syria] is essentially a tactical change - it is not a change in the mission. It does not change the structure, design or authorities on which the campaign has been based". Pompeo added that "in addition to this coalition's laser-like focus on defeating ISIS, we're committed to the following series of things. First, a political solution in line with UN Security Council Resolution 2254. The removal of all Iranian-led forces from Syria". 

Ahead of a ministerial meeting of the counter-ISIS coalition, a senior U.S. official noted that "we're entering a very critical phase in which we need to expand the diplomatic cooperation to assist the populations in Iraq and north-eastern Syria recover from ISIS' rule but also maintaining significant pressure on ISIS as it increasingly turns to insurgent tactics to destabilise both north-eastern Syria and Iraq". Another official further indicated that "our three top priorities [in Syria]... continue to be to secure an enduring defeat of ISIS, to see the exit of all Iranian-commanded forces from the entirety of Syria and to reach a political settlement of the conflicts under UN Security Council Resolution 2254". A third diplomat asserted that "we can't turn a blind eye towards the malign activities of Iran throughout the region", adding that "we expect Iran to fully respect the sovereignty of Iraq and other regional states, to cease their destabilising activities and to refrain from actions that enflame sectarian tensions". 

The IRGC's commander warned Israel to "fear the day when Iranian precision missiles hit you and take revenge of all the blood of oppressed Muslims which you have shed". "Iran will keep in Syria all the military and revolutionary advisors, and equipment and weapons which aim to train and empower Islamic resistance forces and support oppressed people of the country", he pledged, adding that "we do not take into account your ridiculous threats. You know that if we have chosen to wait against your hostile measures, some considerations lie behind it". In related comments, Iran's diplomatic spokesperson advised Prime Minister Netanyahu to "know your limits". 

A senior Iranian military official indicated that "as far as terrorists are in Syria and the country asks help from Tehran, Iran will continue its advisory presence in Syria". 

Via Twitter, President Trump indicated the U.S. was "starting the long overdue pullout from Syria while hitting the little remaining ISIS territorial caliphate hard, and from many directions. [We] will attack again from existing nearby base if it reforms. Will devastate Turkey economically if they hit Kurds. Create 20-mile safe zone..." He went on to add that "[we] do not want the Kurds to provoke Turkey. Russia, Iran and Syria have been the biggest beneficiaries of the long-term U.S. policy of destroying ISIS in Syria - natural enemies". 

Secretary Pompeo affirmed that "the roughly 2,000 uniformed soldiers that are in Syria today are going to be withdrawn. That activity is underway. We’re going to do so in an orderly, deliberate way, a way that protects America’s national security, a way that allows us to continue the important mission that they were on. The counter-terrorism mission, the effort to make sure that the destruction of ISIS is not only complete but that their resurgence is not possible, our efforts to counter the threat from terrorism stemming from the Islamic Republic of Iran – those are all real missions. The tactical change we’ve made in the withdrawal of those 2,000 troops is just that, a tactical change. The mission remains the same". 

Secretary Pompeo acknowledged that the U.S. goal of removing "every Iranian boot on the ground [in Syria] is an ambitious objective... but it's ours. It is our mission". Withdrawing U.S. forces from Syria, Pompeo explained, "is a tactical change. It doesn't materially alter our capacity to continue to perform the military actions that we need to perform. But even more broadly than that, the campaign to create a better world, to allow the Iranian people to have opportunity and democracy, has lots of pieces to it - economic, financial, diplomatic for sure". He went on to suggest that "the nuclear proliferation risks from Iran are incredibly real... our mission set is certainly to stop the terror regime, to stop the fighting of Hizbollah and Shiite militias and the Huthis... but it has a nuclear component". 

Secretary Pompeo pledged that "in Syria, the U.S. will use diplomacy and work with our partners to expel every last Iranian boot". "There will be no U.S. reconstruction assistance for areas of Syria held by Assad", he added, "until Iran and its proxy forces withdraw and until we see irreversible progress towards a political resolution". 

Secretary Pompeo remarked that President Trump has "made a commitment. We're going to withdraw our uniformed personnel, uniformed guys, 2000 roughly folks on the ground. We're going to withdraw them from Syria". 

National Security Advisor John Bolton described the U.S. base at al-Tanf as "still very strategically important in connection with our determination that Iran not achieve this arc of control stretching from Iran through Iraq into Lebanon and Syria". 

A senior U.S. diplomat explained that "concerning Syria, we have no timeline for our military forces to withdraw... the President has made the decision that we will withdraw our military forces from Syria, but that it will be done in a deliberate, heavily coordinated way with our allies and partners". The diplomat went on to assert that "our military posture in Syria may be changing, but our overall goals in Syria remain the same, and key among those is... to see the withdrawal from Syria of all Iranian-commanded forces". 

Secretary Pompeo remarked that "the President is not ambiguous with respect to Syria. Our troops are coming out. The President also made very clear that we needed to continue the counter-ISIS campaign, and we needed to continue to ensure that we did the things to create stability throughout the Middle East. The counter-Iran campaign continues. We'll do all of those things......we will simply do it at a time when the American forces have departed Syria". Pompeo also discussed U.S. sanctions against Iran, stating that while "a well-supplied crude oil market" was a consideration for issuing sanctions waivers, "we want to ensure that we're complying with the requirements that the sanctions on Iran have the ultimate goal which we're trying to achieve: creating an outcome where the Iranian people... can have better lives than they have today under this tyrannical regime". 

President Trump asserted that "Iran is no longer the same country. Iran is pulling people out of Syria. They can do what they want there, frankly. But they're pulling people out. They're pulling people out of Yemen". "When we do all of the things that we've done monetarily to Iran", he added, "Iran is in trouble. And you know what? I'd love to negotiate with Iran. They're not ready yet, I don't think. But they will be. But Iran is a much different country right now... than it was when I took over". Asked about a timetable for pulling U.S. forces out of Syria, Trump responded that it would occur "over a period of time. I never said I'm getting out tomorrow. I said we're pulling our soldiers out, and they will be pulled back in Syria, and we're getting out of Syria... but we're getting out very powerfully". 

President Trump asserted that "ISIS is mostly gone", adding that "we're slowly sending our troops back home to be with their families, while at the same time fighting ISIS remnants". 

Iran's military chief of staff posited that "the U.S. pullout from Syria is a humiliating withdrawal", adding that "wherever Americans have been present, they caused insecurity... the [U.S.] exit from Syria and other parts of the region will lead to enhanced security and calm in the region". 

During a visit to Iraq, President Trump asserted that "there will be a strong, deliberate and orderly withdrawal of U.S. forces from Syria... while maintaining the U.S. presence in Iraq to prevent an ISIS resurgence and to protect U.S. interests, and also to always watch very closely over any potential reformation of ISIS and also to watch over Iran. We'll be watching". The trip drew criticism from Iraqi parliamentarians as well as PMU officials. 

President Trump announced that "Saudi Arabia has now agreed to spend the necessary money needed to help rebuild Syria". 

Foreign Minister Javad Zarif opined that "the U.S. has not fought against ISIS at all, and its presence in Syria is not in line with the interests of the Syria nation or agreed by the [country's] government". He went on to state that, following President Trump's decision to pull U.S. forces out of the country, "we do not have sufficient information on the U.S. plans in Syria to adopt a clear-cut stance". 

President Trump indicated that the U.S. military withdrawal from Syria would be "slow and highly coordinated". 

President Trump asserted that "on Syria, we were originally going to be there for three months, and that was seven years ago - we never left... now ISIS is largely defeated and other local countries, including Turkey, should be able to easily take care of whatever remains". 

Reacting to President Trump's decision to withdraw U.S. forces from Syria, Iran's Foreign Ministry opined that "in principle, the deployment and presence of U.S. forces in the region from the outset was a wrong, irrational and provocative move that created tensions". A senior Iranian military official also weighed in saying that "the Americans have come to the conclusion that they can exercise power neither in Iraq and Syria nor in the entire region". 

Explaining the U.S. decision to withdraw from Syria, Secretary Pompeo stressed that "the primary mission was to go take down the ISIS caliphate. That is at the very tail end of completion. And we have ISIS remnants in lots of pockets around the world". He added that the U.S. "intends to continue that counter-terrorism campaign, continue the fight against ISIS, whether it stems from Syria or other places". 

Elaborating on his decision to withdraw U.S. forces from Syria, President Trump asserted that "getting out of Syria was no surprise... Russia, Iran, Syria and others are the local enemy of ISIS. We were doing there [sic] work. Time to come home and rebuild". He went on to state that "Russia, Iran, Syria and many others are not happy about the U.S. leaving... because now they will have to fight ISIS and others, who they hate, without us." 

Prime Minister Netanyahu revealed that in conversations with President Trump and Secretary Pompeo, "the American administration told me that it is the president's intention to withdraw their forces from Syria. They made it clear that they have other ways of expressing their influence in the area". Netanyahu went on to say that "this is, of course, an American decision. We will study its timetable, how it will be implemented, and - of course - its implications for us. In any case we will take care to maintain the security of Israel and to defend ourselves in this area". 

President Trump announced that "we have defeated ISIS in Syria, my only reason for being there during the Trump presidency", while a White House statement indicated that "we have started returning U.S. troops home as we transition to the next phase of this campaign". 

A senior Russian defence official maintained that the U.S. was "holding with incomprehensible stubbornness the occupied 55-km area around al-Tanf where 6,000 armed militants are on the loose and are preventing the disbanding of the Rukban refugee camp". In related comments, a Russian diplomatic spokesperson suggested that "there is growing concern related to the dubious activity of the U.S. and its allies in Syria. The illegal occupation of the 55-km zone around the base in al-Tanf continues to be the basic source of destabilisation in that part of Syria". 

Referring to the U.S. presence at al-Tanf, Russia's Foreign Ministry remarked that "under the excuse of fighting against ISIS and - as we were told - in order to contain Iran, a big U.S. military base was set up there, in a strategically important area adjacent to the borders of Syria, Iraq and Jordan, which is close to the highway connecting Baghdad and Damascus. And there, according to numerous witness accounts, militant training is underway". 

The U.S. special representative for Syria, James Jeffrey, laid out U.S. objectives in Syria as "the enduring defeat of ISIS, a re-invigorated and irreversible political process... and de-escalation of the conflict that will include all Iranian-commanded forces departing from the entirety of Syria". Jeffrey elaborated that "on getting Iran out, that is basically part of a process. It's not a military goal of the U.S., it's not a mission of U.S. military forces... you will not have a lasting peace in Syria if Iran is doing the kind of power projection policies out of Syria that it has done through Hizbollah in southern Lebanon and done through the Huthis in northern Yemen". 

The U.S. special representative for Syria, James Jeffrey, opined that the "Iranians are part of the problem not part of the solution" in Syria, and noted that the U.S. was "contesting more actively Iran's activities particularly in Iraq, Syria and Yemen". 

Syria's foreign minister, Walid al-Moallem, claimed that "under the pretext of supporting Syria Kurds, the U.S. has established bases in the north of Syria and a base in al-Tanf in the south, which is actually used to reorganise ISIS terrorists to fight the Syrian Arab Army". 

The commander of U.S. Central Command, Joseph Votel, remarked during a visit to the al-Tanf garrison that "we don't have a counter Iranian mission here. We have a defeat ISIS mission. But I do recognise that our presence, our developments of partners and relationships down here does have an indirect effect on some malign activities that Iran and their various proxies and surrogates would like to pursue down here".

A senior U.S. diplomat asserted that "we want to see the Iranians leave Syria... and frankly, even the Russians tell us that's their goal. So there seems to be some consensus that the Iranians and their forces inside Syria should leave Syria". 

Referring to the al-Tanf garrison, a senior Syrian official claimed that the U.S. is "gathering the remnants of ISIS at this base in order to later send them to wage war on the Syria army". 

The U.S. special representative for Syria, James Jeffrey, assessed that Iran's involvement in Syria reflects "capabilities that we would associate with power projection over the region. Very similar to what we've seen in southern Lebanon, very similar to what we have seen in northern Yemen". He went on to suggest that "a military presence long term, including power projection - which the Iranian seem to be aiming for - is a little bit more than their minimum goals and seems to be frosting on the cake. What we're trying to suggest is let's put pressure on them to leave". "We're not going to force the Iranians out of Syria", Jeffrey added. "This is all about political pressure". 

A U.S. military official indicated that military exercises involving U.S. forces and U.S.-backed rebels in al-Tanf "was conducted to reinforce our capabilities and ensure we are ready to respond to any threat to our forces within our area of operations". The Pentagon also confirmed that Russia had been advised of the drills. 

The Pentagon announced a "defeat-ISIS exercise" at the al-Tanf garrison. 

In remarks at the trilateral summit on Syria, President Rouhani urged that "the presence and illegal interference of the U.S. in Syria, which has led to the continuation of insecurity in that country, must be ended immediately". 

U.S. defence officials indicated that Russia had warned of possible operations near al-Tanf to counter "militants" within the de-confliction zone. A Pentagon official remarked that "the U.S. does not seek to fight the government of Syria or any groups that may be providing it support. However, if attacked, the U.S. will not hesitate to use necessary and proportionate force to defend U.S., coalition or partner forces". 

A senior U.S. official indicated that "the new policy [in Syria] is we're no longer pulling out by the end of the year". 

During an encounter with a senior Russian military official, Iran's defence minister, Amir Hatami, estimated that "victories [against terrorists in Syria] are only halfway, and operations need to continue in full coordination, and the military achievements need to be protected in all other arenas". 

Several Iranian and Iran-backed troops were purportedly killed or injured in an airstrike near al-Tanf; the U.S.-led coalition acknowledged that the garrison "received fire from unknown forces" but "did not fire back". 

Elaborating on the 26 August cooperation deal between Iran and Syria, a senior Iranian military official revealed that "the continuation of presence of Iranian [military] advisors in Syria was one of the points of the defence and technical agreement". 

Iran and Syria signed a military cooperation agreement which Iran's defence minister, Amir Hatami, declared would "define the areas of presence, contribution and cooperation between Tehran and Damascus". Hatami also indicated that "Iran's private sector has high enough to capacities to help the Syrian people and government in the reconstruction process", and suggested that Iran "can help Syria to develop military equipment". 

A senior Russian diplomat asserted that "we treat Iran's steps to furnish its own security and activities with great respect, specifically in Syria at the invitation of this country's legitimate government. However, this does not mean that there are no prospects or room for further efforts in this sphere". 

The Russian foreign minister, Sergey Lavrov, suggested that "all foreign forces staying [in Syria] without an invitation from the Syrian government must be eventually withdrawn". 

The U.S. national security advisor, John Bolton, asserted that "our interests in Syria are to finish the destruction of the ISIS territorial caliphate and deal with the continuing threat of ISIS terrorism and to worry about the presence of Iranian militias and regular forces". Bolton added that "we're going to see what we and others can agree in terms of resolving the conflict in Syria. But the one prerequisite there is the withdrawal of all Iranian forces back in Iran". 

A U.S.-backed Syrian rebel group "detained twelve suspicious persons transiting inside the coalition-held 55-km de-confliction zone around Tanf", five of whom were subsequently alleged to be ISIS fighters. 

A senior Russian military official claimed that "the number of ISIS militants has been growing in areas adjacent to the al-Tanf zone controlled by U.S. troops". 

Iran's foreign minister, Javad Zarif, asserted that "we have good communication and coordination with Russia and with the Syrian government and we will continue to do so. Our objective here is very clear, that is our objectives and the objective of the Russian Federation and that is to fight terrorism and extremism". 

An Iranian official opined that "neither Russians nor Europeans are in a position to decide on the withdrawal of Iranian military advisors from Syria".

The U.S. national security advisor, John Bolton, opined that "the president has made it clear that we are [in Syria] until the ISIS territorial caliphate is removed and as long as the Iranian menace continues throughout the Middle East". 

A senior Iranian official remarked that "Iran's presence in Syria and Iraq is advisory and if their respective governments want it, we will leave immediately". He went on to suggest that "the U.S. is seeking to divide Iraq into three parts and Syria to five". 

A senior U.S. diplomat asserted that "we are very serious and determined about re-imposing our sanctions that were lifted under the Iran nuclear deal, and we are working very closely with nations to provide alternatives to the Iranian supply of oil". The official also called on "all nations to be vigilant about Iran using embassies as diplomatic cover to plot terrorist attacks".

The secretary of state, Mike Pompeo, asserted that "the Iranian presence in Syria is not appropriate and will not be tolerated... we are going to undertake along with our partners a comprehensive program to diminish that activity".

The UK reportedly carried out an airstrike against "pro-Syrian regime forces" near al-Tanf in June.  

The U.S. rebuffed reports that it had hit a Syrian military position near al-Tanf, while acknowledging that a U.S.-backed Syrian rebel group was involved in a clash with an "unidentified hostile force" beyond 55-km buffer.

A U.S.-backed Syrian rebel group captured over $1 million worth of drugs from ISIS inside the al-Tanf de-confliction zone. 

Bashar Assad stated that "the Americans say they are ready [to leave Tanf], but everyone knows that the Americans are historically professional liars in politics... we have to wait and see". 

A senior Syrian official cautioned against accepting "statements on an agreement about the south of Syria unless the U.S. withdraws its forces from the al-Tanf area". 

A senior Syrian diplomat asserted that "whether Iranian forces or Hizbollah withdraw or stay in Syria is not up for discussion". 

President Rouhani discussed the U.S.-led strikes on Syria with his Russian counterpart, Vladimir Putin, telling Putin that the "attack on Syria shows that we are facing new problems and issues in the final fight against terrorism in Syria, and we should have more consultation and cooperation". 

Responding to the suspected chemical weapons attack in Douma on 7 April, the U.S., the United Kingdom and France struck targets in Damascus and Homs that the Pentagon characterized as "Syrian chemical weapons infrastructure". According to President Trump, "the purpose of our actions...is to establish a strong deterrent against the production, spread and use of chemical weapons". 

Commenting on the possibility of U.S. strikes in Syria, Russia's envoy to the UN asserted that "the danger of escalation is higher than simply Syria because our military are there... so the situation is very dangerous". 

The White House declared itself "committed to eliminating the small ISIS presence in Syria that our forces have not already eradicated", adding that the U.S. "will continue to consult with our allies and friends regarding future plans". 

The Russian foreign ministry expressed its concern over "reports... about the arrival of heavy weapons in the zone around al-Tanf". 

President Trump declared that "we're knocking the hell out of ISIS. We'll be coming out of Syria... very soon". 

Russia's foreign ministry argued that "the U.S. military's illegal presence near al-Tanf and its blocking of the important transport link between Damascus and Baghdad is a blatant violation of Syria's sovereignty". 

Iranian media reported claims that the U.S. had dispatched 600 soldiers to al-Tanf

Russia's foreign minister, Sergey Lavrov, declared that "the unilateral steps made by the U.S., which declared the 55-km area near al-Tanf its zone if influence is something we did not agree on". Claiming that the area is used by jihadists to "recover moral and physical strength" and as a launching area for operations elsewhere, Lavrov urged that the "zone must be closed immediately". 

Following U.S. Secretary of State Tillerson's 17 January speech on Syria policy, the Syrian government maintained "that a U.S. military presence in Syria was illegitimate... and an aggression on Syria's national sovereignty".

 In testimony to the Senate Foreign Relations Committee, a top state department official, David Satterfield, asserted that the U.S. "seek[s] to not only diminish Iranian foreign influence in Syria generally, but to protect our allies from the very real threat Hizbollah poses in southwest Syria to our allies".

The chief of the Russian military’s general staff, Valery Gerasimov, claimed that the U.S. base at al-Tanf was being used to train approximately 350 fighters who “are practically Islamic State”. Gerasimov added that U.S. justifications for maintaining the garrison at al-Tanf were “ambiguous”.

The U.S. special presidential envoy for the anti-ISIS coalition, Brett McGurk, declared that “we are present at Tanf, and we’re going to be present at Tanf to make sure ISIS cannot return and also to manage [the] difficult humanitarian situation” at the Rukban camp on the Syrian-Jordanian border.

Twenty ISIS fighters were killed in a clash with the U.S.-backed Syrian rebel group Maghawir a-Thawra (MaT) near al-Tanf. An unspecified number were detained. The U.S.-led coalition supported MaT forces during the engagement. 

U.S.-backed Syrian opposition forces clashed with ISIS forces that entered into the no-go zone.

Forces allied with the Syrian regime breached the de-confliction zone.

A commander of Iraq’s Popular Mobilization Units said an attack on an Iran-backed Iraqi militia deployed in Syria, the Sayyad al-Shuhada Brigades, near al-Tanf killed an estimated 30 of its fighters; ISIS claimed responsibility, but Sayyad al-Shuhada accused the U.S. of involvement. U.S. forces denied any role in the incident.

Reuters reported that the U.S.  strengthened its presence in al-Tanf in mid-June 2017, including through the deployment of high mobility artillery rocket systems, with an estimated range of up to 300km.

U.S.-led forces announced that they had  struck “pro-[Syrian] regime” troops and vehicles in response to the latter’s movement into the de-confliction zone. That month also saw multiple instances of drones – Iranian-made Shahed 129s, possibly controlled by Iran’s IRGC – shot down by U.S. forces close to the garrison.

The U.S. conducted airstrikes against a pro-regime convoy moving in the direction of the garrison. Iranian officials told Crisis Group that the incident was the result of confusion about the nature of the de-confliction zone, which they said they believed was only a no-fly zone; speaking privately, some U.S. officials confirmed to Crisis Group that there had been a misunderstanding.