Does Trump Have the Legal Authority to Strike Iran? An Expert Explains

After building up a massive military force in the Middle East over the last few weeks, President Donald Trump said Friday that he was considering strikes against Iran to pressure its leaders into accepting a deal on its nuclear program. Trump has ratcheted up threats of action against the country’s leadership in recent months alongside a steady buildup of military forces. Two aircraft carriers are currently deployed, and one more—the USS Gerald Ford—is expected to arrive imminently.When questioned by reporters on Friday whether he was weighing limited strikes against the country’s leadership in order to get it to accept a deal over its nuclear program, Trump replied: “I guess I can say I am considering that.”  Read More: Leavitt Says Iran Would Be ‘Wise to Make a Deal’ as Trump Escalates Military Buildup in RegionOn Thursday, Trump gave Tehran a deadline of 10 to 15 days to finalize a deal to solve the nuclear dispute or face “really bad things.” The United States joined an Israeli-led military operation against Iran in June last year that struck three of the country’s nuclear sites. After that operation, Trump claimed Iran’s nuclear enrichment facilities had been “completely and totally obliterated.” Trump raised the prospect of further military action against Iran following a brutal crackdown on protests there that killed thousands. That prospect has drawn harsh criticism from inside and outside of the President’s own party. Rep. Thomas Massie, a Republican, and Rep. Ro Khanna said they would table a War Powers resolution to prohibit the president from ordering military action in Iran without congressional approval.  “Congress must vote on war according to our Constitution. Rep. Ro Khanna and I will be forcing that vote to happen in the House as soon as possible,” Massie wrote on X on Feb. 18. “I will vote to put America first which means voting against more war in the Middle East.”David Janovsky, Acting Director of The Constitution Project at the Project on Government Oversight, answered TIME’s questions about the legality of potential strikes on Iran. If Trump orders strikes on Iran tomorrow, however limited in scope, could that be legally justified? DJ: The short answer is no. There’s no indication that there’s any sort of circumstance that would give the President the unilateral authority to order military action. It’s true that presidents have some inherent authority to deploy the military as Commander in Chief, but that’s really limited to true emergency circumstances where there is an attack underway that needs to be repelled, or maybe an extremely clear imminent attack. But there’s no suggestion that that’s the case today—that would make the strikes illegal. What steps would the White House need to take for this military action to be legally above board? DJ: Most simply, the administration would need to go to Congress. This is a contemplated attack against a sovereign state, and that, in simplest terms, is an act of war. And the Constitution gives the exclusive power to declare war to Congress, not the president. So this is something that would need a vote and congressional approval. How would this operation be different from the strikes on Iran’s nuclear sites in June 2025, legally speaking? DJ: My position is that those strikes in 2025 were not legally justifiable and also that strikes now would likewise not be justifiable. In 2025, the administration put out a very brief explanation that relied on both the President’s inherent authority and a notion of collective self-defense with Israel. But again, self-defense is properly understood to involve a threat that is much more immediate than anything that’s at play now. What would be the legal and political implications if Congress passed a formal War Powers resolution restricting the President’s ability to strike Iran? DJ: It’s important to keep in mind that if Congress did nothing, that would be a sign that Congress didn’t approve an act of war, and so it would be illegal. So, congressional action isn’t necessary, legally speaking, to prevent a strike against Iran. But, if Congress were to take the preemptive step of saying, “You cannot do this,” I think it would do two things. First, it would change the legal calculus, because the executive branch, for decades— this is not a new phenomenon—has resorted to creative lawyering to come up with excuses for using the military abroad. A clear statement from Congress should at least make those executive branch lawyers a lot less willing to push the envelope. It could also change the calculus for the military lawyers who would need to review any actual strike order.  And, politically, I think it would send a powerful message. We have seen, especially recently, that the administration is sensitive to losing support, particularly from its allies in Congress, and a clear congressional statement that there is not the buy-in for military action in this case would also be a limiting factor. Why has the reaction from Congress to this military buildup been so muted? DJ: I think there are probably both long-term structural reasons and sort of short-term political reasons, hand in hand with the executive branch’s decades-long effort to push the envelope of what it can do has been Congress’s acquiescence in the face of those expansions. In some ways, this is part of a constitutionally very dangerous but long-running trend. Back in 2025, there was an effort after the strikes to pass a war powers resolution. But the most charitable explanation for why Congress didn’t act then was that there was a suggestion that the strikes were over and done. It was a one-off, and there was no need for Congress to prevent anything else. The fact that we’re back here suggests that was not the correct assessment, and certainly underscores the need for Congress to act urgently now.