Renewed Tensions in the Persian Gulf: Further War Powers Lessons from the Tanker War
Renewed Tensions in the Persian Gulf: Further War Powers Lessons from the Tanker War
Op-Ed / United States 14 minutes

Renewed Tensions in the Persian Gulf: Further War Powers Lessons from the Tanker War

For years, Iran has been attacking and seizing commercial vessels in the Persian Gulf, in some cases seemingly in retaliation for U.S. efforts to interdict Iranian oil exports as a sanctions enforcement measure. These moves have raised fears about regional maritime security in the Strait of Hormuz, a narrow waterway that remains critical to the global oil supply. The United States has responded to recent Iranian action by deploying F-16, F-35, and A-10 warplanes to the region, along with additional warships, and U.S. forces, including the 26th Marine Expeditionary Unit. According to press reports, the Biden administration is now also deliberating over whether to station U.S. Marines on commercial tankers, whether to expand “collective self-defense” to vessels based on ownership of the ship or cargo (rather than solely based on U.S. registration), as well as potentially delegating further down the chain of command the authority of military commanders to use force.

The intent behind the proposal to station Marines aboard commercial vessels appears to be to use U.S. armed forces as a tripwire, whereby any Iranian attack on these commercial vessels would amount to an attack on U.S. armed forces. The apparent logic is that such a tripwire would deter Iran from further attacks or attempts to seize tankers or other commercial vessels.

The extension of the United States’ defensive umbrella over commercial vessels in the Persian Gulf has historic precedent, most prominently during the so-called Tanker War. In response to Iranian attacks on neutral oil tankers, the United States agreed to reflag Kuwaiti vessels as American and accompany them with U.S. naval convoys as part of Operation Earnest Will. As the Legal Adviser to the State Department argued at the time, “U.S. protection of the vessels is intended to deter rather than provoke military action by Iran.” In the event, this operation led to repeated hostilities between U.S. and Iranian forces in 1987-1988.

The Reagan administration’s military operations in the Gulf in 1987-1988 raised important legal issues under the War Powers Resolution that may bear both on contemplated operations in the region today as well as Congress’s efforts to reform and reinforce that 1973 law. (My former State Department colleague Todd Buchwald previously discussed some of the legal issues implicated by the Tanker Wars in this Just Security piece.) The Tanker War also illustrates how measures taken ostensibly for deterrence can lead to escalation and draw the United States deeper into conflict. Despite a recently announced U.S.-Iran prisoner release arrangement, in the context of continued tensions over Iran’s nuclear program and tit-for-tat hostilities in the region, concerns that history may repeat itself are more than theoretical.

Legal Background: The 1973 War Powers Resolution

The statutory framework intended to govern the unilateral use of force by the president, both in the Tanker War and in the event U.S. armed forces again interpose themselves between attacking Iranian ships and commercial vessels, is the War Powers Resolution. Congress enacted this law over President Nixon’s veto in 1973 to reassert its constitutional prerogatives with respect to war and peace in the final stages of the Vietnam War. Specifically, Congress sought to forestall any president from taking the country to war without congressional authorization or even without congressional awareness (as had allegedly been the case for aspects of the war in Indochina, such as the incursion into Cambodia).

To this end, Section 4(a) of the Resolution establishes reporting requirements to prevent the president from taking the country to war in secret. In the absence of a declaration of war or other statutory authorization, the president is subject to multi-tiered obligations to report on certain triggering activities of U.S. armed forces within 48 hours to Congress. First, under subsection 4(a)(1) she must report when U.S. military forces are introduced into “hostilities” or introduced into “situations where imminent involvement in hostilities is clearly indicated by the circumstances.” Such hostilities reports are the focus of this essay. Second, even if U.S. forces are not engaging in hostilities, subsection 4(a)(2) requires the president to report the introduction of “combat equipped” forces into a country (which the executive branch reads as forces equipped with crew-served weapons such as machine guns requiring more than one person to operate and mortars). Third, pursuant to subsection 4(a)(3) the president must also report a substantial enlargement of such combat equipped forces in a country where such forces are already present.

Notably, under Section 5(b) of the 1973 Resolution, the submission of a report under the first of these scenarios — introduction of U.S. forces into hostilities or situations of imminent hostilities — also starts a 60-day clock for the withdrawal of U.S. armed forces from such hostilities unless Congress declares war or otherwise enacts specific statutory authorization for the use of force.  Further, the War Powers Resolution provided a mechanism in section 5(c) for Congress to order the removal of U.S. forces from hostilities through a concurrent resolution—that is, a resolution passed by both houses of Congress but not presented to the president for his or her signature or veto. (Particularly following the Supreme Court’s 1983 decision in INS v. Chadha that ruled unconstitutional the legislative veto, section 5(c) is widely viewed as unconstitutional. In the wake of Chadha Congress enacted expedited procedures for joint resolutions requiring the removal of U.S. armed forces from hostilities, which does require presentment to the president.)

Although Congress did not define “hostilities” or “imminent involvement in hostilities,” in the text of the statute, the legislative history indicates that Congress intended those terms to be construed broadly in order to establish a low threshold for both the reporting and withdrawal provisions of the War Powers Resolution. The House Foreign Affairs Committee’s report on the Resolution explains:

The word hostilities was substituted for the phrase armed conflict during the subcommittee drafting process because it was considered to be somewhat broader in scope.  In addition to a situation in which fighting actually has begun, hostilities also encompasses a state of confrontation in which no shots have been fired but where there is a clear and present danger of armed conflict. “Imminent hostilities” denotes a situation in which there is a clear potential either for such a state of confrontation or for actual armed conflict.

Unsurprisingly, the executive branch has espoused different, narrower interpretations of these terms that are less likely to constrain the president’s ability to use military force without congressional authorization. In the most oft-repeated formulation, the State Department’s Legal Adviser informed Congress in a 1975 letter that its working definition of “hostilities” meant “a situation in which units of the U.S. armed forces are actively engaged in exchanges of fire with opposing units of hostile forces.” “Imminent hostilities” means “a situation in which there is a serious risk from hostile fire to the safety of United States forces.” As a matter of statutory interpretation, it is questionable how much weight the post-enactment views of the executive branch should be accorded as opposed to the pre-enactment interpretation of the legislature that enacted the statute over the president’s veto.

The Failure of Deterrence: Active Conflict and Tragedy

The Tanker War was waged in the context of the broader 1980-88 Iran-Iraq War. In 1984, Iraq began to attack tankers carrying Iranian oil through the Persian Gulf in an attempt to make up at sea the military momentum it was losing on land. Iran reciprocated, though by targeting vessels carrying the oil of Arab states it viewed as supporting Iraq in the conflict. By 1987, Iran and Iraq had attacked 259 oil tankers/product carriers in the Gulf.

In late 1986, Iran began stepping up attacks on Kuwaiti-flagged vessels as well as vessels bound to or from Kuwait. In response, Kuwait approached the United States and other states (including the Soviet Union) about protecting vessels carrying its oils. The United States and Kuwait agreed on a plan to reflag 11 vessels as American. The Reagan administration announced that it would “provide the same type of protection for Kuwaiti reflagged vessels as that accorded other U.S.- flagged vessels operating in the gulf.” The stated rationale for the move was both to deter Iran from further attacks but also to limit the influence of the Soviet Union in the Gulf.  In July 1987, the United States initiated naval convoys under the moniker Operation Earnest Will.

Even prior to the launch of Operation Earnest Will, U.S. forces in the Gulf had come under fire. On May 17, 1987, an Iraqi fighter jet mistakenly attacked the U.S.S. Stark killing 37 U.S. sailors.

During the ten-month course of the operation—the largest naval convoy operation since the Second World War— U.S. forces and the commercial vessels they were escorting were repeatedly involved in fighting, beginning with the very first convoy when the SS Bridgeton struck an Iranian mine on July 24.  Following this incident, the U.S. posture shifted from one of more passive deterrence, including for example by pursuing the Iranian minelayers. Moreover, U.S. forces respond to an October 16 Iranian missile attack on the reflagged SS Sea Isle City by destroying an Iranian oil platform. Fighting between U.S. and Iranian forces intensified in particular after the USS Samuel B. Roberts struck an Iranian mine on April 14, 1988 and almost sank. In a retaliatory attack on April 18, dubbed Operation Praying Mantis, U.S. forces destroyed two Iranian oil platforms, several speedboats, damaged the frigate Saban, and destroyed the frigate Joshan. In addition to attacks on Iranian military assets, during the course of these U.S. operations in the Gulf, the USS Vincennes also mistakenly shot down Iran Air Flight 655 killing 290 civilians. In all, the Reagan administration reported six incidents to Congress occurring between September 21, 1987 and July 12, 1988.

Avoiding the 60-day Clock

The Reagan administration employed several techniques to avoid the 60-day deadline imposed by the War Powers Resolution for terminating hostilities during the U.S. engagement in the Tanker War. In addition to contending that the termination provision of Section 5 was unconstitutional (a reversal from the position taken by the DOJ’s Office of Legal Counsel under President Carter), the Reagan administration interpreted key provisions of the War Powers Resolution narrowly and exploited loopholes in the law to continue hostilities against Iran beyond 60 days.

Narrow Interpretation of “Hostilities”

Both in the lead up and during the implementation of the reflagging and escort operation, the Reagan administration construed the terms “hostilities” and “imminent hostilities” extremely narrowly to avoid triggering either the reporting or withdrawal provisions of the Resolution.  For example, following the Iraqi missile attack on the U.S.S. Stark on May 17, 1987 prior to the escort operation, the executive branch did not report the incident to Congress under the War Powers Resolution as seemingly required. Instead, Secretary of State Schultz sent the Speaker of the House what might be termed an “anti-War Powers” report—a letter that, though it did not mention the law itself, explicitly denied that U.S. armed forces were in hostilities or situation of imminent hostilities:

Our forces are not in a situation of actual hostilities, nor does their continued presence in the area place them in a situation in which imminent involvement in hostilities is indicated, although we are mindful of recent Iranian statements threatening U.S. and other ships under protection.

Similarly, when on August 10 a U.S. F-14 fighter fired two missiles at an unidentified target it deemed a threat, even though the missiles missed, Congress asked why the event did not constitute “involvement in imminent hostilities” and thus trigger the War Powers Resolution.  In a letter to the Chairman of the House Foreign Relations Committee, the State Department took the position that “[i]solated incidents involving defensive reactions by U.S. forces do not necessarily indicate that imminent involvement in hostilities is clearly indicated by the circumstances… In this particular case, it is not clear that an attack on U.S. forces was imminent, and in fact no such attack occurred.”

When the Pentagon announced the U.S. military personnel in the Persian Gulf would be eligible to receive “imminent danger” pay, Congress pressed the administration as to why the conditions justifying such pay did not also trigger the application of the War Powers Resolution.  The administration sought to distinguish the standard for “imminent danger” pay from “hostilities” under the War Powers Resolution, claiming that the former was much broader than the latter. These narrow interpretations of the terms “hostilities” and “imminent hostilities” were nothing new for the Reagan administration, as it had previously resisted notifying U.S. military operations in El Salvador—despite multiple U.S. servicemembers being killed by hostile fire and a lawsuit brought by members of Congress.

Slippery Reports and Salami Slicing

When the Reagan administration eventually did submit reports to Congress that referenced the War Powers Resolution, the framing and content of the documents were designed to avoid either triggering or running out the Resolution’s 60-day clock.

In the first place, the reports (all of which can be found at War Powers Resolution Reporting Project of the Reiss Center on Law and Security at NYU School of Law) emphasized that the administration challenged the constitutionality of certain unspecified provisions of the Resolution. Second, the reports were generally submitted “consistent with” the Resolution (the now-standard formulation used by the executive branch) rather than pursuant to, even though no administration has seriously challenged the constitutionality or binding nature of the reporting requirements of the law.

Further, even though the events described in these reports clearly involved “hostilities” even under the executive branch’s narrow interpretation, the Reagan administration (as had already become typical) did not specify under which provision of the Resolution it was reporting these incidents. In doing so, it could claim that it had never triggered the 60-day clock for withdrawing from hostilities that would be activated by a report submitted under Section 4(a)(1) of the law. The Reagan administration was candid about exploiting a loophole in the law, as the Resolution did not require the president to identify the reason he or she was submitting a report. As Abe Sofaer, the State Department’s Legal Adviser, later explained:

[Section 4] does not require the President to state the particular subsection under which reports are made no President has felt compelled to do so. A definitive judgment at the outset of a deployment as to whether hostilities will result is often difficult to make, and this practices is a useful way…for the Executive to avoid unnecessary constitutional confrontations over whether section 4(a)(1) is applicable or whether, even if its conditions are met, it can properly be deemed to trigger an automatic termination under section 5.

Finally, the Reagan administration treated ongoing hostilities between U.S. and Iranian forces as a series of discrete events. Its reports to Congress on these hostilities sometimes noted that the administration “considered the matter closed.” Filing multiple reports for what was in fact a single, continuing conflict over the course of at least ten months, allowed the executive branch to stop and reset the 60-day clock for withdrawing from hostilities. (The Obama administration would later adopt a similar “salami-slicing” approach during the early months of the counter-ISIS campaign by filing multiple War Powers reports for that conflict.) As Todd Buchwald noted, there is tension between the Reagan administration treating these incidents as discrete for the purposes of the War Powers Resolution and the United States aggregating them for the purposes of its international law arguments before the International Court of Justice in the Oil Platforms case. In its arguments for the International Court of Justice, the United States contended that the proportionality of measures the U.S. took in self-defense should not be assessed based merely on the immediately preceding Iranian attack, but by the overall threat posed by Iran—including by looking at the “recurring pattern of attacks.”

Inconclusive Congressional Action

Given the Reagan administration’s efforts to avoid triggering subsection 4(a)(1) of the Resolution, members of Congress – principally in the Senate – sought to force the application of the Resolution through legislation. For example, one measure in the Senate would have legislatively determined that subsection 4(a)(1) had been triggered thus forcing the start of the 60-day clock, which would require the subsequent removal of U.S. forces from hostilities unless Congress passed a use of force authorization. There was recent precedent for such action as Congress had retroactively determined by a joint resolution in 1983 that “the requirements of section 4(a)(1) of the War Powers Resolution became operative on August 29, 1983” with respect to U.S. miliary operations in Lebanon but also provided limited authority for continued U.S. operations in that country for 18 months. However, unlike in 1983, such measures, including a proposed amendment to the National Defense Authorization Act for Fiscal Year 1988, did not pass the Senate much less both houses of Congress. Moreover, they were opposed by the Reagan administration.

Rather than enact substantive restrictions on the use of force, Congress settled for passing a requirement for a report from the Pentagon prior to the implementation of any reflagging agreement with Kuwait. The episode illustrates the difficulty Congress faces in pushing back in the moment against a unilateral use of force by a president, including the hurdle of marshalling a congressional majority, much less a supermajority to block a war in progress, when the White House skirts the strictures imposed by the War Powers Resolution.

Ineffective Litigation

Members of Congress also sought to enforce the War Powers Resolution through recourse to the courts. In Lowry v. Reagan, 110 members of the House of Representative joined a suit against President Reagan seeking to compel him to file report under section 4(a)(1) of the Resolution and thus started the 60-day clock for withdrawal from hostilities. The district court judge dismissed the suit, including on the basis of the political question doctrine. (The court also noted in dicta that in light of the Supreme Court’s decision in INS v. Chadha, the concurrent resolution mechanism of the War Powers Resolution for forcing the withdrawal of U.S. forces did not have the “force and effect of law,” a point apparently conceded by the plaintiffs.) The court’s avoidance of the merits of the suit is typical of the response by judiciary to attempts by Congress to resolve disputes over war powers in the courts.


Although the context of the Tanker War was very different than the current situation in the Persian Gulf, the conflict nonetheless demonstrates how measures taken in the name of defense can lead to escalation. The episode highlights how the threat of the use of force against Iran for the ostensible purpose of deterrence can instead result in an unpredictable and spiraling conflict.

The Tanker War also illustrates how the shortcomings of the War Powers Resolution combined with the machinations of an obdurate executive branch and the legislature’s own dysfunctions, hobble Congress’s ability to exercise its constitutional prerogatives and restrain the president from taking provocative unilateral military action. Recognizing the inadequacies of the Resolution, the Senate Foreign Relations Committee formed a special subcommittee on War Powers chaired by then-Senator Joe Biden. Although the subcommittee held a number of hearings and Senator Biden elaborated on the Resolution’s shortcomings and proposed his own replacement in a law review article, Congress did not ultimately fix the flaws in the law.  

As the United States faces renewed military tensions in the Persian Gulf, bipartisan coalitions in Congress are once again attempting to reinforce the weak guardrails of the War Powers Resolution. In the House, these efforts take the form of the National Security Reform and Accountability Act (NSRAA) recently reintroduced by Representatives Jim McGovern (D-MA) and Nancy Mace (R-SC). Amongst other things, this bill would define key terms like “hostilities” in the War Powers Resolution and give that law teeth by imposing an automatic funding cutoff for conflict not authorized by Congress within 20 days of the introduction of U.S. forces into “hostilities or a situation where there is a serious risk of hostilities.” Along with a companion piece of legislation, the National Security Powers Act (NSPA), introduced in the Senate during the last Congress, these measures would implement recommendations originally proposed by the late legal scholar John Hart Ely following the Tanker War. Although the short-term prospects for the enactment of this legislation either in whole or in part are uncertain, the possibility of the White House unilaterally introducing U.S. armed forces into yet another potential conflict in the Middle East should generate a sense of urgency on Capitol Hill for finally tackling the long overdue project of war powers reform.

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