CIA Director John Ratcliffe, Secretary of State Marco Rubio, Defence Secretary Pete Hegseth and General Dan Caine, chairman of the Joint Chiefs of Staff, came to Capitol Hill to give the classified briefings, originally scheduled for Tuesday.

Many Republicans left satisfied, though their assessments of how much Iran’s nuclear program was set back by the bombing varied. Senator Tom Cotton said a “major blow” and “catastrophic damage” had been dealt to Iran’s facilities.

Democrats, and some Republicans, have said the White House overstepped its authority when it failed to seek the advice of Congress.

They also want to know more about the intelligence that Trump relied on when he authorised the attacks.

A similar briefing for House members will be held later today.

A preliminary US intelligence report found that Iran’s nuclear program had been set back only a few months, contradicting statements from Trump and Israeli Prime Minister Benjamin Netanyahu about the status of Iran’s nuclear facilities, according to two people familiar with the report.

They were not authorised to discuss the matter publicly and spoke on condition of anonymity.

“You want to call it destroyed, you want to call it defeated, you want to call it obliterated – choose your word. This was an historically successful attack,” Hegseth said at a Pentagon briefing.

On Wednesday, Director of National Intelligence Tulsi Gabbard and Ratcliffe sent out statements backing Trump’s claims that the facilities were “completely and fully obliterated”.

Gabbard posted on social media that “new intelligence confirms what @POTUS has stated numerous times: Iran’s nuclear facilities have been destroyed”.

She said that if the Iranians choose to rebuild the three facilities, it would “likely take years to do”.

Ratcliffe said in a statement from the CIA that Iran’s nuclear program has been “severely damaged”.

He cited new intelligence “from a historically reliable and accurate source/method that several key Iranian nuclear facilities were destroyed and would have to be rebuilt over the course of years”.

Most Republicans have defended Trump and hailed the tentative ceasefire he brokered in the Israel-Iran war.

House Speaker Mike Johnson went as far as to question the constitutionality of the War Powers Act, which is intended to give Congress a say in military action.

“The bottom line is the commander in chief is the president, the military reports to the president, and the person empowered to act on the nation’s behalf is the president,” Johnson told reporters.

But some Republicans, including some of Trump’s staunchest supporters, are uncomfortable with the strikes and the potential for US involvement in an extended Middle East conflict.

“I think the speaker needs to review the Constitution,” Senator Rand Paul said.

“And I think there’s a lot of evidence that our Founding Fathers did not want presidents to unilaterally go to war.”

Paul would not say whether he would vote for the resolution by Senator Tim Kaine that would require congressional approval for specific military action in Iran.

A simple majority in the Senate is needed to pass the resolution and Republicans hold a 53-47 advantage.

“I will have Republican votes, plural,” Kaine said.

“But whether it’s two or 10, I don’t know.”

Kaine authored a similar resolution in 2020 aimed at limiting Trump’s authority to launch military operations against Iran.

At the time, eight Republicans joined Democrats in approving the resolution.

“I think I have a chance to get some votes from people who are glad that President Trump did this over the weekend, but they’re saying, ‘Ok, but now if we’re really going to go to war, it should only have to go through the Congress,'” Kaine told The Associated Press before the briefing.

While Trump did not seek approval, he sent congressional leaders a short letter Monday serving as his official notice of the strikes, which occurred Saturday between 6.40pm and 7.05pm EDT (8.40am to 9.05am Sunday AEST).

The letter said the strike was taken “to advance vital United States national interests, and in collective self-defence of our ally, Israel, by eliminating Iran’s nuclear program.”