Iran was planning attacks on four US embassies when its top general was killed, President Donald Trump says.
When asked what threat led to last Friday's US drone strike, he told Fox News: "I can reveal that I believe it probably would've been four embassies."
The killing of Gen Qasem Soleimani, a national hero, came after days of protests at the US embassy in Baghdad.
But Democrats given intelligence briefings on the fatal strike say they have seen no evidence of embassy plots.
Mr Trump first made the embassy claim at the White House on Thursday and repeated it that night at a rally in Ohio.
He was also backed up by US Secretary of State Mike Pompeo.
"We had specific information on an imminent threat and those included attacks on US embassies. Period, full stop," said Mr Pompeo as he announced new sanctions against Iran.
Soleimani, 62, was the mastermind of Iran's activities in the Middle East, as an architect of the Syrian government's war against rebels and the rise of pro-Iranian paramilitaries in Iraq.
Mr Trump and Mr Pompeo have said he was responsible for the deaths of thousands.
American forces also targeted Abdul Reza Shahlai on 3 January, a key Iranian commander and financier living in Yemen, US media reported on Friday.
They quote unnamed US officials as saying that the secret mission did not result in the commander's death.
Washington has so far made no public comment on the reported US raid in Yemen.
What did Trump say?
His first comments on the matter were at an environmental event at the White House on Thursday, telling reporters he authorised the attack because Iran was "looking to blow up our embassy".
He also called it "obvious" that the protesters that attacked the US embassy in Baghdad days before Soleimani's death were organised by Iran.
"And you know who organised it. That man right now is not around any longer. Okay? And he had more than that particular embassy in mind."
In Ohio later, Mr Trump told a packed arena that "Soleimani was actively planning new attacks, and he was looking very seriously at our embassies, and not just the embassy in Baghdad".
He also mocked Democrats who complained that the White House did not provide proper notification to lawmakers, saying that Democrats would have leaked the US military plans to the media.
What evidence is there?
Mr Trump referred to the US embassy protests as evidence of an imminent Iranian plot. However, those protests had ended by the time the US launched a drone attack on Soleimani's motorcade at the Baghdad airport.
House Armed Services committee chairman Adam Smith, a Democrat, said there was "no evidence" of a future Iranian bombing attack on a US embassy presented during a classified White House briefing given to lawmakers on Wednesday.
"Nobody that I've talked to in any setting, and I've talked to quite a few people in the White House, has said that," he told Politico.
"It has been communicated to me that there weren't specific targets, that the intel that we had did not cite specific targets, just more of a broad thing," he said.
"So if the president had evidence of the specific target, that has not been communicated to us."
Vermont Senator Bernie Sanders, a frontrunner to take on Mr Trump in November's election, said Mr Trump could not be trusted.
"The difficulty that we have, and I don't mean to be rude here, is that we have a president who is a pathological liar," he told NBC News.
"So could it be true? I guess it could be. Is it likely to be true? Probably not," he added.
Democrats are not the only ones who have appeared to grow frustrated by the lack of details from the White House regarding why Soleimani's death was urgently required.
Utah Republican Senator Mike Lee slammed the White House briefing as "insulting" and "completely unacceptable".
He called the briefing a "drive-by notification or after-the-fact, lame briefing", adding that officials "struggled to identify" any reason that the White House would ever co-ordinate with Congress on military actions.
On Thursday, the US House of Representatives voted to limit Mr Trump's ability to wage war on Iran.
On Friday, the White House authorised new sanctions against Iran that were designed to "stop the Iranian regime's global terrorist activities", US Treasury Secretary Steve Mnuchin said.
He said the penalties would affect Iran's construction, manufacturing and mining industries. Mr Pompeo said the targets were Iran's "inner security apparatus".
In a statement, Mr Trump called Iran the "world's leading sponsor of terrorism" and vowed to counter Iranian threats "until the Iranian regime changes its behaviour".