Updated March 4, 2026 at 4:38 PM CST
Before President Trump launched a massive military campaign against Iran on Saturday, he collaborated with Israel’s government but didn’t ask Congress for permission to strike another country.
The Constitution gives Congress the power to declare war, but designates the president as the commander-in-chief of the military, which has long caused political conflict.
“Declarations of war are long gone,” said Princeton University historian Julian Zelizer. “It’s not since World War II that Congress has done that.”
5 questions with Julian Zelizer
An authorization to use military force is different from declaring war. In 1950, who sent troops to South Korea? And why was that a turning point?
“It’s a real turning point. That’s [former] President Harry Truman, and he’s relying on directives from the United Nations rather than from Congress, and it’s called a police action rather than a war. And historians say that’s a real change, because that’s when presidents started to feel freed up to avoid that request for a declaration of war.”
You write that when presidents historically asked Congress for some authorization for major military actions, they often lied.
Former President Lyndon B. Johnson persuaded Congress to escalate the Vietnam War based on reported attacks that never happened. Former President George W. Bush claimed Iraq had weapons of mass destruction to gain authorization to attack. Couldn’t a president just skip the lie and do what they want?
“The Constitution vests this power in Congress. The War Powers Resolution of 1973 creates timetables. And even if presidents have lied, manipulated information, what was different than what we’re seeing today is they were still forced to make some case. They were still forced to try to build support on Capitol Hill.
“Right now, we’re in a situation where all of that really went by the wayside. So, you know, even if a president looks back and says, ‘I’d rather do it myself,’ that doesn’t mean they can.”
Can you explain more about the War Powers Resolution of 1973?
“It was an effort to reclaim the power that had been lost since World War II. Congress passes the resolution, and it basically sets up different timetables that a president has time to send troops, but then has to get congressional approval, and timetables when that approval expires. So, it was definitely not perfect, and as we’ve seen, presidents have found ways around them. But it was an effort in 1973 to reassert the role of Congress in war power.”
Does it even matter if Congress votes now?
“The cynical view is this is already happening, so what’s the difference if Congress now approves it? And I think that’s right. That’s why this should happen before the president sends troops, especially in a war like this, where there’s no imminent threat.
“But it still matters. Any effort of Congress to assert itself at this point is something. That something is better than nothing, which is where we are. So, if there was a bipartisan push for this, I think it would at least create some framework for the next time around, where Congress could draw on this precedent and say, ‘You need to ask us for this permission.’”
What is the significance of military action in Venezuela just two months ago?
“I think the president feels pretty free. He did what he wanted to do. He didn’t consult Congress, and there was no pushback from the Republican Congress.
“So, besides it being relatively quick and successful, I think he learned a lesson: He can do unilaterally whatever he wants, and he can get away with it.”
This interview was edited for clarity.
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Jenna Griffiths produced and edited this interview for broadcast with Michael Scotto. Grace Griffin produced it for the web.
This article was originally published on WBUR.org.
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