According to President Trump, the United States attacked Iran because the Islamic Republic posed “imminent threats” to the U.S. and its allies, including through its use of terrorist proxies and continued pursuit of nuclear weapons.

“Its menacing activities directly endanger the United States, our troops, our bases overseas and our allies throughout the world,” he said in a recorded statement Saturday.

According to leading Democrats in Congress, Trump’s justification is questionable, especially given his claims of having “completely obliterated” Iran’s nuclear capabilities in separate U.S. bombings last June.

“Everything I have heard from the administration before and after these strikes on Iran confirms this is a war of choice with no strategic endgame,” said Rep. Jim Himes (D-Conn.), ranking Democrat on the House Intelligence Committee and part of a small group of congressional leaders — the Gang of Eight — who were briefed on the operation by Secretary of State Marco Rubio.

That divide is bound to remain an issue politically heading into this year’s midterm elections, and could be a liability for Republicans — especially considering that some in the “America First” wing of the MAGA base were raising their own objections, citing Trump’s 2024 campaign pledges to extricate the U.S. from foreign wars, not start new ones.

The debate echoed a similar if less immediate one around President George W. Bush’s decision to go to war in Iraq following the Sept. 11, 2001, attacks, also based on claims that “weapons of mass destruction” posed an immediate threat. Those claims were later disproved by multiple findings that Iraq had no such arsenal, fueling recriminations from both political parties for years.

The latest divide also intensified unease over Congress ceding its wartime powers to the White House, which for years has assumed sweeping authority to attack foreign adversaries without direct congressional input in the name of addressing terrorism or preventing immediate harm to the nation or its troops.

Even prior to the weekend bombings, Democrats including Sen. Adam Schiff of California were pushing Congress to pass a resolution barring the Trump administration from attacking Iran without explicit congressional authorization.

“President Trump must come to Congress before using military force unless absolutely necessary to defend the United States from an imminent attack,” Sen. Tim Kaine (D-Va.), a member of the armed services and foreign relations committees, said in a statement Thursday.

In justifying the daylight strikes that killed Supreme Leader Ayatollah Ali Khamenei just two days later, Trump accused the Iranian government of having “waged an unending campaign of bloodshed and mass murder” for nearly half a century — including through attacks on U.S. military assets and commercial shipping vessels abroad — and of having “armed, trained and funded terrorist militias” in multiple countries, including Hezbollah and Hamas.

Trump said that after the U.S. bombed Iran last summer, it had warned Tehran “never to resume” its pursuit of nuclear weapons. “Instead, they attempted to rebuild their nuclear program and to continue developing long-range missiles that can now threaten our very good friends and allies in Europe, our troops stationed overseas, and could soon reach the American homeland,” he said.

Other Republican leaders largely backed the president.

“The United States did not start this conflict, but we will finish it. If you kill or threaten Americans anywhere in the world — as Iran has — then we will hunt you down, and we will kill you,” said Defense Secretary Pete Hegseth.

“Every president has talked about the threat posed by the Iranian regime. President Trump is the one with the courage to take bold, decisive action,” said Atty. Gen. Pam Bondi.

While Iran’s coordination with and sponsorship of groups such as Hezbollah and Hamas are well known, Trump’s claims about Tehran’s ongoing development of nuclear weapons systems are less established — and the administration has provided little evidence to back them up.

Democrats seized on that lack of fresh intelligence in their responses to the attacks, contrasting Trump’s latest statements about imminent threats with his assertion after last year’s bombings that the U.S. had all but eliminated Iran’s nuclear aspirations.

“Let’s be clear: The Iranian regime is horrible. But I have seen no imminent threat to the United States that would justify putting American troops in harm’s way,” said Sen. Mark Warner (D-Va.), vice chairman of the Senate Intelligence Committee and a member of the Gang of Eight. “What is the motivation here? Is it Iran’s nuclear program? Their missiles? Regime change?”

Senate Minority Leader Chuck Schumer (D-N.Y.) said in a statement that the Trump administration “has not provided Congress and the American people with critical details about the scope and immediacy of the threat,” and must do so.

House Minority Leader Hakeem Jeffries (D-N.Y.) said the Trump administration needs congressional authority to wage such attacks barring “exigent circumstances,” and didn’t have it.

“The Trump administration must explain itself to the American people and Congress immediately, provide an ironclad justification for this act of war, clearly define the national security objective and articulate a plan to avoid another costly, prolonged military quagmire in the Middle East,” he said.

After the U.S. military announced Sunday that three U.S. service personnel were killed and five others seriously wounded in the attacks, the demands for a clearer justification and new constraints on Trump only increased.

Rep. Ro Khanna (D-Fremont) said Sunday he is optimistic that Democrats will be unified in trying to pass the war powers resolution, and also that some Republicans will join them, given that the strikes have been unpopular among a portion of the MAGA base.

Rep. Thomas Massie (R-Ky.), who partnered with Khanna to force the release of the Jeffrey Epstein files, has said he will work with him again to push a congressional vote on war with Iran, which he said was “not ‘America First.’”

Benjamin Radd, a political scientist and senior fellow at the UCLA Burkle Center for International Relations, said that whether or not Iran represented an “imminent” threat to the U.S. depends not just on its nuclear capabilities, but on its broader desire and ability to inflict pain on the U.S. and its allies — as was made clear to both the U.S. and Israel after the Hamas attacks on Israel on Oct. 7, 2023, which Iran praised.

“If you are Israel or the United States, that’s imminent,” he said.

What happens next, Radd said, will largely depend on whether remaining Iranian leaders stick to Khamenei’s hard-line policies, or decide to negotiate anew with the U.S. He expects they might do the latter, because “it’s a fundamentalist regime, it’s not a suicidal regime,” and it’s now clear that the U.S. and Israel have the capabilities to take out Iranian leaders, Iran has little ability to defend itself, and China and Russia are not rushing to its aid.

How the strikes are viewed moving forward may also depend on what those leaders decide to do next, said Kevan Harris, an associate professor of sociology who teaches courses on Iran and Middle East politics at the UCLA International Institute.

If the conflict remains relatively contained, it could become a political win for Trump, with questions about the justification falling away. But if it spirals out of control, such questions are likely to only grow, as occurred in Iraq when things started to deteriorate there, he said.

Israel and the U.S. are betting that the conflict will remain manageable, which could turn out to be true, Harris said, but “the problem with war is you never really know what might happen.”

On Sunday, Iran launched retaliatory attacks on Israel and the wider Gulf region. Trump said the campaign against Iran continued “unabated,” though he may be willing to negotiate with the nation’s new leaders. It was unclear when Congress might take up the war powers measure.