US President Donald Trump sent letters to members of Congress on Friday (May 1), claiming that the War Powers Act did not apply because a ceasefire was currently underway.He was referring to a 1973 US law that mandates presidents to withdraw troops within 60 days if they were deployed without Congressional clearance.Trump’s letters to House Speaker Mike Johnson and Senate President pro tempore Chuck Grassley reiterated the administration’s line that the April 7 ceasefire had effectively stopped that clock.“On April 7, 2026, I ordered a two-week ceasefire. The ceasefire has since been extended. There has been no exchange of fire between the United States Forces and Iran since April 7, 2026. The hostilities that began on February 28, 2026, have terminated,” Trump wrote in the letters.The letters described the “changes in the posture” of the US forces in West Asia, and an assurance that he would “keep the Congress fully informed, consistent with the War Powers Resolution.” Trump separately told reporters, “I don’t think it’s constitutional” for Congress to seek authorisation.Analysts have argued that the continued presence of the US military in the region keeps the provision in play. US forces had fired on an Iranian-flagged cargo ship on April 19, a fact Trump notably omitted in his letters.Under the 1973 War Powers Resolution, presidents who deploy US forces into hostilities without congressional authorisation must end the operation after 60 days, unless Congress votes for their continued deployment. Congress must be notified within 48 hours of troop deployment. The law also grants the president 30 days only to safely bring troops home, not to extend combat.This is determined by two sections of the law:Story continues below this adSection 4 requires the president to submit a report to Congress within 48 hours of introducing American troops into “hostilities” and to explain the constitutional and legislative authority under which the action was taken, the basis for the action, and the estimated scope and duration of the US involvement.Once that is done, a 60-day clock is triggered under Section 5.Since Trump formally notified Congress of the deployment of US forces on March 2, the statutory end-date was May 1.The law is automatically invoked, without Congress having to pass a resolution to implement it or vote on the subject.Also Read | India-bound LPG tanker on the move across Strait of Hormuz. Why it mattersWhile Congress did not declare or authorise the war thus far, Republicans have blocked several Democratic Party-led efforts to limit Trump’s ability to act without congressional approval, or to end the war.What necessitated this law?The need for such a resolution arose from the division of war powers in the US Constitution. Article I, Section 8 authorises Congress to declare war and take steps towards the same, as well as authorising states to “Appoint the Officers of the Militia”; and “train the Militia according to the discipline prescribed by Congress.” Article II, Section 2, on the other hand, recognises the US president as the Commander in Chief of the US army and navy, as well as of the militia of the several States, when called into the actual service of the US.Story continues below this adThe law itself was enacted after successive presidents dragged the nation into Vietnam without congressional approval. The resolution was passed by a two-thirds congressional majority despite then-President Richard Nixon’s veto. The law ended up reasserting congressional authority over the president, following Nixon’s secret bombing of Cambodia during the Vietnam War without congressional permission.One chief condition for the law was the presence of a “national emergency created by attack upon the United States, its territories or possessions, or its armed forces”.After deploying Marines to Beirut in 1982, Ronald Reagan was forced to report to Congress under the law.Presidents have often exercised their unilateral authority by bypassing the Act, citing international resolutions or broad authorisations, such as the post-9/11 Authorizations for Use of Military Force (AUMF) in Afghanistan and Iraq.Story continues below this adAs president, Barack Obama sought to bypass the law by claiming it did not apply during the US’s military operations in Libya in 2011, triggering debates over whether “hostilities” persisted.How is the Act relevant now?Despite Trump’s claims about a complete cessation in hostilities since the ceasefire started, the continued presence of the US military near Iran has arguably kept the Resolution in play. Legal scholars have argued that the 60-day clock applies from when forces are introduced into hostilities, and not from when the last shot was fired. This implies that the ceasefire does not stop the clock, only lowers the tensions at play.The Obama administration had made a similar argument in 2011, claiming that its drone operations over Libya did not constitute “hostilities” under the Resolution. This was a position broadly rejected by Congress and legal scholars. Trump’s ceasefire argument follows the same logic and faces the same objection.Jasmine Farrier, professor of Political Science at the University of Louisville, argues in an article for The Conversation that a separate challenge arose in 1983 when the US Supreme Court struck down legislative vetoes as unconstitutional. Thus, Congress was forced to reinterpret its own War Powers processes. Instead of cessation of military action automatically at the 60-day mark, Congress must now proactively pass a disapproval resolution, which the president can veto. Such a veto can only be overridden by a two-thirds majority in both chambers. Effectively, Congress will now have to vote twice to stop a conflict it never approved in the first place.Story continues below this adUS-Iran War | Why the US-Iran ceasefire is on thin ice: 5 things to knowDespite the ceasefire, the US is responsible for a blockade of all vessels headed to and from Iranian ports. On April 19, USS Spruance, a US destroyer, fired “several rounds” towards the Iranian-flagged ship, Touska, that was headed to an Iranian port in violation of the US blockade. “After Touska’s crew failed to comply with repeated warnings over a six-hour period, Spruance directed the vessel to evacuate its engine room,” US Central Command said in a statement.This attack, as well as the fact that the US has “directed 25 commercial vessels to turn around or return to an Iranian port”, undermines Trump’s claim that hostilities have fully “terminated”. It also raises a separate question: whether a naval blockade, enforced by live fire, constitutes an ongoing act of war regardless of what the president calls it.Why this war may play out differentlyThe war has proven to be especially unpopular. A Pew Research Center study in March 2026 noted that nearly two-thirds of Americans surveyed disapproved of the war. Unlike past instances, such as Reagan’s Beirut deployment or Obama’s Libya operations — where the White House faced some political blowback from its own party — Trump’s Iran operations have fractured Republican unity ahead of the midterms. Faced with increasingly difficult midterm prospects, House Republicans have expressed an uncharacteristic willingness to go against Trump.Also of note, the War Powers Resolution has never been meaningfully challenged in the US Supreme Court. Federal courts have also consistently rejected War Powers lawsuits brought by members of Congress, most recently following Clinton’s Kosovo operation in 1999 and Obama’s Libya campaign in 2011. In both cases, courts declined to rule on the merits, finding that lawmakers lacked standing to sue. Democrats are reportedly considering a similar lawsuit if operations continue past May 1, but are faced with a slim legal precedent in their favour.Story continues below this adNewsletterFollow our daily newsletter so you never miss anything important. On Wednesday, we answer readers' questions.SubscribeFarrier argues that the Kosovo and Libya episodes helped establish the War Powers Resolution’s 60-day clock less as a hard legal deadline and more as a politically charged symbol of a longstanding imbalance in war powers. In both cases, military operations ran ambiguously well past the deadline without Congressional approval or disapproval. In 1999, NATO suspended operations after 78 days, while Obama’s Libya campaign ran 222 days under similar legal ambiguity. In both cases, the conflict ended before the constitutional standoff was resolved.With US troops still engaged beyond May 1, the War Powers Act is now being tested in ways it hasn’t been in over 50 years.