As many expected, the Trump administration has persisted in waging its war on Iran without congressional authorization. In doing so, the White House continues to act in violation of not only the U.S. Constitution and the UN Charter, but also the 60-day deadline on unauthorized hostilities imposed by the War Powers Resolution (WPR), as we have each argued before. What’s new is the White House argument in a May 1st letter to Congress that the WPR’s 60-day clock stopped because the “hostilities that began on February 28, 2026, have terminated” with the Apr. 7 ceasefire between the United States and Iran.
The administration’s argument fails both because it relies on a deeply flawed definition of the term “hostilities” and because the objective facts of ongoing U.S. military operations, notwithstanding the partial ceasefire, constitute “hostilities” even under that flawed interpretation. Although the administration’s legal theory, in broad terms, is hardly unprecedented, it is even more unconvincing than attempts by President Donald Trump’s predecessors to circumvent the 60-day clock.
This article explains why the Trump administration’s legal theory is unavailing and examines previous executive branch attempts to circumvent the 60-day clock. The Iran War makes plain why the WPR still matters, and also the need for structural reform to give the law sharper teeth. In the short term, Congress has the opportunity to take immediate bipartisan steps to check further military adventurism by the White House using its power of the purse and considerable oversight authority.
Legal Background: What Does “Hostilities” Mean in the War Powers Resolution?
The War Powers Resolution is a landmark statutory framework intended to restore the constitutional balance over the use of military force. As originally enacted, it gave Congress tools to rein in unilateral action by the executive – without having to mount veto-proof supermajorities in both chambers. And it seeks to prevent any president from taking the country to war without congressional authorization or even without congressional awareness. The law is designed to do this through a framework requiring, on the front end, consultation and notification before American forces are in harm’s way (its transparency forcing provisions) and, on the back end,termination of military operations if the president is unable to get Congress to support the military action (its teeth). The termination provisions include the automatic withdrawal provision now colloquially referred to as the “60-day clock.”
Specifically, section 4(a) of the WPR 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 required to report to Congress within 48 hours of certain activities abroad by U.S. armed forces, and must periodically update Congress on ongoing situations at least every six months. The requirement to report the introduction of U.S. military forces into “hostilities” or “situations where imminent involvement in hostilities is clearly indicated by the circumstances” is the most consequential, because it is those reports that trigger the 60-day clock that is the focus of our analysis.
The WPR has two mechanisms to terminate unilateral deployments into hostilities or imminent hostilities. As originally enacted, section 5(c) provides 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 signature or veto. Especially following the Supreme Court’s 1983 decision in INS v. Chadha that ruled unconstitutional the so-called legislative veto, section 5(c) is widely viewed as unconstitutional. Following Chadha, Congress enacted expedited procedures for joint resolutions requiring the removal of U.S. armed forces from hostilities, which do require presentment to the president. That means Congress now needs supermajorities to overcome a presidential veto of a withdrawal resolution under the WPR. This is, of course, a complete inversion of the constitutional framework: under Article I, a majority in Congress is needed to authorize war in the first place, but now, supermajorities must be mustered to overcome unilateral presidential warmaking.
But there is another backstop. Under Section 5(b) of the WPR, the submission of a 48-hour report on the introduction of U.S. forces into hostilities or situations of imminent hostilities starts a 60-day clock for the withdrawal of U.S. armed forces from such situations unless Congress declares war or otherwise enacts specific statutory authorization for the use of force. Congress needs to take no action for the termination provision to become effective. It is mandatory. And that’s why the definition of the term “hostilities” has taken on heightened importance over the decades – if unauthorized “hostilities” are ongoing at 60 days, they must stop. But if the military actions at issue don’t constitute “hostilities,” or if the“hostilities” have ended, the clock becomes irrelevant.
Although Congress did not define “hostilities” or “imminent involvement in hostilities” in the text of the WPR, the legislative history shows that Congress clearly intended those terms to be construed broadly to establish a low threshold for both the reporting and withdrawal provisions of the WPR. 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. (emphases added)
Yet, since the first few years following the WPR’s enactment, 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, according to the letter, “a situation in which there is a serious risk from hostile fire to the safety of United States forces.”
What to do with those competing views? As a matter of statutory interpretation, it would be dubious to assign greater weight to the post-enactment views of the executive branch that tried to veto the statute than to the pre-enactment interpretation of the legislature that passed the statute over the president’s veto.
The Trump Administration’s 60-Day Clock Argument
On May 1, the Trump administration told Congress that hostilities with Iran had ended, and thus the 60-day clock stopped ticking:
On April 7, 2026, I ordered a 2-week ceasefire. The ceasefire has since been extended. There has been no exchange of fire between United States Forces and Iran since April 7, 2026. The hostilities that began on February 28, 2026, have terminated.
The President’s letter to Congress does explicitly concede that “hostilities” began on Feb. 28, which is notable as the executive branch across administrations typically avoids such outright acknowledgements, ostensibly to preserve operational flexibility (that is, to leave room for potential doubt as to whether it was an introduction into hostilities or one of the other triggers for 48-hour reporting, like the introduction of combat-equipped forces into a foreign country, that necessitated the report).
Importantly, this letter did not argue that the WPR is unconstitutional as the President himself had suggested earlier in that very day. We have rebutted that claim previously.
Nor did the letter advance the narrower, but still demonstrably false claim that every previous president has rejected the 60-day clock as unconstitutional, as asserted in this recent Washington Post opinion essay. As the Department of Justice’s Office of Legal Counsel (OLC) noted in 1979, “the only provision that this Administration has suggested presents constitutional problems related to the right of Congress to act by concurrent resolution.” OLC took the position in a 1980 opinion that “Congress may, as a general constitutional matter, place a 60-day limit on the use of our armed forces as required by the provisions of § 1544(b) of the Resolution.” In 1993, OLC took the position that “in most circumstances the time limit of § 5(b) would not unconstitutionally restrict the President’s ability to exercise his inherent authority regarding the use of force.” And, in 2011, the State Department’s legal adviser told Congress, in the context of the Libya operation, “[W]e have made it clear that we are not challenging the constitutionality of the resolution.”
Why the Administration’s Argument Fails
The administration’s argument that the 60-day clock is no longer ticking fails for two separate reasons.
First, the administration’s interpretation of “hostilities” (one frequently relied on by the executive branch since 1975), is inconsistent with Congress’s understanding of that term as reflected in the legislative history of the WPR. As explained above, Congress understood hostilities to be broader than the term “armed conflict” and thus to encompass “a state of confrontation in which no shots have been fired but where there is a clear and present danger of armed conflict.” Although Congress would have been on much stronger footing had the language in the House report made it into a “Definitions” section of the bill, it has long been inappropriate for the executive branch to essentially ignore the very clear legislative history that does exist and instead substitute its own preferred interpretation.
It is unquestionable that the war on Iran that began on Feb. 28 has involved much more than “a state of confrontation.” (Indeed the Trump administration has acknowledged that U.S. forces have been engaged in an international armed conflict with Iran.) To say that we’re well past the threshold where shots have been fired, of course, would be a gross understatement – 13 U.S. service members have been killed and hundreds injured, a majority of U.S. sites in the region have reportedly suffered a total cost of many billions of dollars in damage, thousands of people have died in Iran, the war expanded across the region to multiple countries where missiles and drones and other weapons systems have been deployed extensively.
The only question, then, is whether this state of confrontation continued beyond the “ceasefire” referenced in the May 1 letter. This cannot be answered with reference to the letter itself, because it doesn’t just cherry pick the most convenient facts for the president’s case, but in fact leaves out all of the relevant facts after the April 7 ceasefire announcement. It does not mention at all the naval blockade that the United States enforces against Iran—itself an act of war and use of force under international law. As one of us (Tess) and Oona Hathaway explained when Secretary of Defense Pete Hegseth advanced the “ceasefire stopped the clock” argument in a Senate hearing prior to the May 1 letter:
The Secretary of Defense is clearly wrong about the law. The ongoing U.S. naval blockade of Iranian ports, as well as U.S. forces firing on and seizing Iranian vessels in military operations are acts of war, and clearly present ongoing significant risk to U.S. troops. Indeed, the administration is trying to have it both ways–arguing on the one hand that we have been in hostilities with Iran since 1979 and yet we are not currently in hostilities with Iran at the moment and thus the clock is paused. Both arguments are belied by the facts. The “ceasefire paused the clock” argument does not pass the test of seriousness.
For removal of any doubt, we note that the Supreme Court, DOJ’s Office of Legal Counsel (“a blockade is a belligerent act”), and the U.S. Department of Defense all unequivocally consider a blockade to be an act of war. As the Supreme Court held in the Prize Cases, the “proclamation of blockade is itself official and conclusive evidence to the Court that a state of war exist[s].” Given the legal significance of even pronouncing a blockade, the executive branch has sometimes avoided using the term. The Kennedy administration famously resorted to the euphemism of “quarantine” with respect to its naval operations during the Cuban Missile Crisis. The George H.W. Bush administration similarly shied away from the term with respect to naval operations against Iraq in 1990 following the invasion of Kuwait.
Moreover, the ongoing confrontation with Iran also involves the broader U.S. military buildup in the Middle East, and Trump’s regular threats of further military action against Iran—including threats of widescale war crimes.
In sum, Congress chose the term “hostilities” to be broader than armed conflict. Instead, the Trump administration, like others before it, is suggesting the opposite, but in circumstances where the common sense interpretation of the facts on the ground (active enforcement of a naval blockade) make it even more implausible.
Indeed, the very same day the White House sent this letter to Congress, President Trump himself appeared to reject its key argument. At a political event in Florida, he announced in the present tense, “We’re in a war”, referring (correctly) to the situation with Iran. At another point during the same event, Trump indicated he was advised to use the term “military operation” rather than “war” to avoid legal problems. And then again on May 4th, President Trump referred to the war with Iran in the present tense – because that’s common sense.
Second, even under the narrow executive branch interpretation, U.S. armed forces have engaged in “hostilities” since the April 7th ceasefire took effect. Contrary to the claim in the May 1st letter that there “has been no exchange of fire between the United States and Iran since April 7, 2026,” the U.S. Navy has subsequently fired on Iranian vessels and other Iranian entities to enforce the naval blockade.
On April 19th, a U.S. navy destroyer fired on the M/V Toushka, disabling it, after which U.S. Marines descended from helicopters to seize the vessel. (U.S. forces continued to hold these Iranian sailors in custody until May 3rd, when they were repatriated to Iran by Pakistan acting as an intermediary.) And on May 4th, following the administration’s announcement of “Project Freedom” (an apparent effort to loosen Iran’s grip on the Strait), U.S. forces shot down Iranian drones and cruise missiles aimed at vessels in the Strait of Hormuz and destroyed six Iranian military speedboats threatening commercial shipping. In a briefing on May 5th, Chairman of the Joint Staff General Dan Caine stated that since the ceasefire, Iran had attacked U.S. forces more than ten times.
…But is Not Unprecedented–Legal Gamesmanship to Avoid the 60-Day Clock
Although the Trump administration’s argument that the 60-day clock is not ticking because hostilities have supposedly been terminated is unavailing and novel as applied to the ongoing enforcement of a naval blockade, the notion of starting and stopping the clock is hardly unprecedented.
Administrations of both parties have repeatedly advanced similar arguments in attempts to skirt the 60-day deadline and continue military operations without congressional authorization. Such arguments have generally taken one of two forms.
Military Operations No Longer Constitute Hostilities
Some administrations have claimed at the 60-day mark (like this White House with respect to Iran) that ongoing military operations no longer amount to “hostilities” and thus the restrictions of the WPR did not apply.
Boat Strikes (Trump 2.0)
The Trump administration claimed in November 2025 that its still ongoing maritime bombing campaign against alleged drug trafficking vessels in the Caribbean and eastern Pacific did not constitute hostilities and therefore it could continue bombing boats without congressional authorization. An anonymous senior administration official told the Washington Post that the WPR doesn’t apply to the maritime strikes because, “even at its broadest … [it] has been understood to apply to placing U.S. service-members in harm’s way.” According to this official, “[t]he operation comprises precise strikes conducted largely by unmanned aerial vehicles launched from naval vessels in international waters at distances too far away for the crews of the targeted vessels to endanger American personnel.” Thus, “the kinetic operations underway do not rise to the level of ‘hostilities,’” according to the administration.
As one of us wrote at the time, this argument regarding hostilities was flawed, including in light of the WPR’s legislative history. It’s likewise unavailing because the same type of strikes, conducted by crews far from the targeted vessels, were reported on Sept. 2, 2025 – the reason for the report could only have been that the strikes were considered “hostilities,” given there was no combat-equipped introduction of U.S. forces into another country’s territory, airspace or waters or substantial enlargement of such a contingent (i.e., the other two reporting prongs were clearly not at issue). That means the very same acts, against the same types of actors, in the same theater of operations, were “hostilities” on Sept. 2 but were not hostilities come November.
2011 Libya Intervention (Obama)
The Obama administration advanced a similar argument that its role in the 2011 NATO bombing campaign in Libya no longer constituted “hostilities” and thus those U.S. military operations did not have to cease at the 60-day mark.
Despite the opposing view of the Office of Legal Counsel, the Obama administration ultimately adopted the position that U.S. operations—including airstrikes—did not amount to “hostilities” despite having initially reported them as such. It argued, pointing to past executive branch practice interpreting the WPR, that there were not “hostilities” due to a combination of four factors:
- The U.S. mission was limited in scope, and involved U.S. forces playing a “supporting role” for NATO in implementing a U.N. Security Council Resolution.
- The exposure of U.S. armed forces to harm was limited, including because of the absence of ground troops (and no effective threat to air operations).
- The risk of escalation was limited, again due to the absence of U.S. ground forces.
- Military means used by the United States were limited, with airstrikes being “confined, on an as-needed basis, to the suppression of enemy air defenses to enforce the no-fly zone, and to limited strikes by Predator unmanned aerial vehicles against discrete targets in support of the civilian protection mission.”
The Obama administration’s interpretation of “hostilities” was not well received by the Senate Foreign Relations Committee, under the Chairmanship of Sen. John Kerry (D-MA), which approved legislation on a strong bipartisan basis stating that:
United States military operations in Libya since April 4, 2011, which have included non-kinetic support to the NATO-led operations, including intelligence, logistical support, and search and rescue assistance, United States aircraft assisting in the suppression and destruction of air defenses in support of the no-fly zone, and precision strikes by unmanned aerial vehicles, constitute hostilities within the meaning of the War Powers Resolution, and may be carried out only under the conditions specified in section 5(b) of the War Powers Resolution (50 U.S.C. 1544(b)).
Stopping and Restarting the 60-Day Clock
Multiple administrations have relied on the separate argument, either explicitly or implicitly, that unauthorized military operations could continue beyond 60-days because the clock stopped and restarted, what one of us (Brian) has termed the “salami-slicing” approach. Reliance on this theory is usually accompanied by the filing of multiple War Powers reports, each one associated with notionally discrete episodes of hostilities.
Should the Trump administration resume military operations against Iran beyond the naval blockade (options for which are reportedly under consideration), it may argue that the 60-day clock has stopped and then restarted. Notably, the administration did not file a new report after it seized an Iranian vessel by force less than two weeks into the “ceasefire.” Given U.S. military action against Iranian projectiles and vessels in the Strait of Hormuz on May 4th, the administration may now pivot to argue that the clock stopped and restarted – if a 48-hour report is filed on May 6, we expect that to be the official argument.
Here are examples of how “discrete incident reporting” has been used since the 1980s:
Tanker War (Reagan)
The Reagan administration pioneered the salami-slicing approach during U.S. military operations against Iran in the Tanker War of 1987-88 in the Persian Gulf. 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 with each exchange of fire – and terminating its claimed exercise of self-defense (unlike an ongoing blockade).
As Todd Buchwald noted, there was tension between the Reagan administration treating these incidents as discrete for the purposes of the WPR 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 before the International Court of Justice, the United States contended that the proportionality of measures the United States 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.”
The Trump administration is not the first to find its international law and War Powers arguments in conflict, although the scale of that inconsistency is arguably even greater here given the intensity of its war with Iran.
Counter-ISIS (Obama)
The Obama administration also used this “salami slicing” tactic during the early phase of the military campaign against the so-called Islamic State. In June 2014, it filed repeated notifications under the WPR for incidents that were sometimes only a few days apart. Initially treating these airstrikes against ISIS as discrete incidents was a good faith effort by the administration to report separate operations (an airdrop aimed at relieving the siege of Mount Sinjar, airstrikes to protect Mosul Dam). But during August and September 2014, the Obama administration submitted a series of near weekly reports that demonstrated a higher tempo of airstrikes on ISIS in what was becoming an ongoing military campaign.
Notably, the administration did not sustain that approach and instead pivoted to the argument that the strikes came under the umbrella of the 2001 Authorization for Use of Military Force (AUMF), a different way to moot the War Powers Resolution issue.
Iran-Backed Militias (Biden)
Between October 2023 (following Hamas’s October 7th attack on Israel) and January 2024, the Biden administration filed repeated war powers 48-hour reports in connection with retaliatory U.S. military actions against Iran-backed militias in Iraq and Syria in response to their operations against U.S. forces in those countries. The administration sought to treat these hostilities as discrete incidents, suggesting that the 60-day clock stopped and restarted with each reported set of operations.
Structural Reform for a Chronic War Powers Problem
President Trump’s Iran War illustrates both chronic and acute pathologies involving the exercise of war powers by the U.S. government.
The Trump administration is not the first to stretch the law – by advancing an exceedingly narrow definition of “hostilities” or making strained arguments about the 60-day termination clock starting and stopping – in the service of enabling and justifying unauthorized military action.
Unfortunately, this war is yet another reminder among many of the need for structural reform of the WPR. Viable reform proposals exist, and have been introduced on a bipartisan basis, in both the House and Senate. As these proposals do, any revision of the WPR should include defining key terms like“hostilities,” significantly shortening the deadline for terminating unauthorized hostilities, and enforcing that deadline through mandatory funding cutoffs.
While some of these proposals may be viable on their own and could be included in other “must-pass” legislative vehicles (like the next National Defense Authorization Act), the political reality is that broader structural reform will most likely need to be enacted over a presidential veto, and is thus unlikely during this administration. Congress passed the WPR with a bicameral supermajority that overcame President Nixon’s veto – but replicating that in today’s polarized political climate is hard to imagine. Overhauling the statute is likely to be a longer term fix for a chronic problem.
A Case Apart
The familiarity of the administration’s formal legal claims for continuing the Iran War should not obscure the truly aberrant manner in which President Trump has used (and threatened) military force against Iran and elsewhere in his second term. Even against the background of increased presidential unilateralism in recent decades, Trump’s military adventurism is a marked departure.
The Iran War is the most significant military action without congressional authorization since the Korean War (and indeed, since the WPR’s enactment). Trump’s war has killed and injured thousands (including U.S. service members), displaced millions, cost the United States tens of billions to wage (in addition to the costs to American consumers), caused still worsening economic pain around the globe, and diverted U.S. military resources away from other allies and regions. It may also have long-term geostrategic implications that are only beginning to take shape while the war is still underway.
As one of us wrote recently, the Iran War is triply illegal—violating the U.S. Constitution, UN Charter, and now the WPR. During the course of the conflict, the president has threatened to commit war crimes and even possibly genocide, according to Amnesty International. The war has further damaged both domestic and international safeguards against the use of force and harmed U.S. alliances and standing in the world.
It has been a legal, humanitarian, and strategic debacle.
And of course, Operation Epic Fury is hardly the only military action President Trump has conducted in his second term. In just the last six months, his administration has bombed not just Iran, but Nigeria, Somalia, Syria, Iraq, Venezuela, and (possibly) Ecuador, in addition to continuing its premeditated killing campaign in the Caribbean and the Pacific. None of these actions were undertaken pursuant to fresh congressional authorization (a few are purportedly under the 2001 AUMF), and several of the largest and most consequential (Iran, Venezuela, the vessel strikes) had none at all. Making matters worse, the President continues to threaten military action against Cuba, and possibly against drug traffickers in Mexico, alongside his on-again, off-again threats against Greenland–the territory of NATO ally Denmark.
Members of Congress and the U.S. public who seek to uphold the Constitution’s allocation of war powers are thus faced with an acute and immediate problem of how to check further military adventurism by this White House.
Congressional Democrats, with some Republican support, have already been forcing regular votes on resolutions opposing further unauthorized hostilities with Iran in both houses of Congress. Thus far, these resolutions have not resulted in more than a handful of GOP members crossing the aisle (Senator Collins–facing a re-election challenge–voted for the most recent resolution). The regular votes do, however, elevate the political and public salience of the conflict and force members to take a position on Congress’s constitutional responsibilities. The debate-forcing and agenda-setting functions of the WPR make it an invaluable instrument , despite its obvious imperfections.
The other tool available to Congress, even the congressional minority, is what some have termed the ultimate war power—the power of the purse. Congress can legislatively prohibit funding for further unauthorized military operations. Failing that, a more likely scenario given the need to overcome a veto for any legislation, the minority in the current Congress opposed to presidential military adventurism can simply refuse to vote for further funding. As one of us wrote in March:
[I]naction could potentially force practical constraints on hostilities against Iran. A supplemental funding bill would require 60 votes in the Senate for passage – given there were 47 votes in favor of affirmatively ending the president’s use of armed force against Iran in the recent War Powers Resolution vote, opponents of these hostilities have a real chance of defeating a supplemental appropriations bill. … The power of the purse is one of the few mechanisms available to the minority in Congress (specifically in the Senate) who oppose further unnecessary and imprudent presidential warmaking to put real pressure on the executive.
Conclusion
As the Supreme Court noted in the Prize Cases in addressing the issue of President Lincoln’s blockade of southern ports during the Civil War, the President “has no power to initiate or declare a war either against a foreign nation or a domestic State.” Trump’s war on Iran illustrates all too clearly why the Constitution does not leave decisions on initiating war to the whims of one person, but instead requires the prior public debate and decision making of the people’s elected representatives in Congress.
It is now, yet again, Congress’s responsibility to assert its constitutional prerogatives with respect to the use of force and more generally rein in a lawless executive. And it is in turn the responsibility of the U.S. public to hold elected representatives accountable if political leaders fail to discharge their constitutional duties.
