Trump says damage to Iran's nuclear sites is 'far below ground level'

The leaders of France, the United Kingdom and Germany released a joint statement on Sunday following the United States' strikes on Iran.

"We reiterate our commitment to peace and stability for all countries in the region," the statement posted to French President Emmanuel Macron's official website said.

"We affirm our support for Israel's security," the leaders continued, saying, "We have always been clear that Iran can never have a nuclear weapon and can never again pose a threat to regional security."

Macron, along withthe UK's Prime Minister Keir Starmer and German Chancellor Friedrich Merz called on Iran to "engage in negotiations leading to an agreement that addresses all concerns related to its nuclear program."

"We urge Iran to refrain from further actions that could destabilize the region," the leaders added.

President Donald Trump appeared to float the idea that there should be a change in leadership in Iran in a new social media post on Sunday. Trump said that though it is "not politically correct" to discuss a regime change, he criticized the current leadership in Iran and also asked, "Why wouldn’t there be a Regime change???"

"It’s not politically correct to use the term, “Regime Change,” but if the current Iranian Regime is unable to MAKE IRAN GREAT AGAIN, why wouldn’t there be a Regime change???," Trump wrote in the brief post on his social media platform, Truth Social.

"MIGA!!!," Trump added in the post, a twist on the MAGA term that he coined.

In an earlier post on Sunday, Trump touted the success of the U.S. strikes on Iranian nuclear sites.

"The damage to the Nuclear sites in Iran is said to be 'monumental.' The hits were hard and accurate," Trump wrote.

-ABC News' Michelle Stoddart

Former CIA officer, U.S. Deputy Assistant Secretary of Defense for the Middle East and ABC News contributor Michael "Mick" Mulroy estimates that the U.S. military operation “likely set back the Iranian nuclear weapons program 2-5 years,” based on the type and amount of munitions used, but told ABC News that the full battle damage assessment will give a more accurate determination.

“The question now is whether this ends this conflict, starts another or least escalates it. That seems to be largely up to Iran,” Mulroy added.

Another former senior U.S. official with direct knowledge of the planning of this strike says Mulroy's assessment is correct in that the U.S. strike likely only set Iran back "a limited number of years," but also says there are ways of extending that.

-ABC News' Selina Wang and Matt Gutman

Rep. Jim Himes, the ranking Democrat on the House Intelligence Committee, said it was too early to know the success of a series of U.S. attacks against Iran – calling the strikes a "massive gamble" on the part of President Donald Trump and citing past U.S. military action in the region.

"I mean, we've seen this movie before. Every conflict in the Middle East has its Senator Tom Cotton who promised us mushroom clouds," Himes told ABC News' "This Week" co-anchor Jonathan Karl.

"In the Iraq war, it was Condoleezza Rice promising us a mushroom cloud. And initially – and this is true of every one of these wars, in Libya ... in Iraq and Afghanistan – initially, things look pretty good," Himes continued. "Saddam Hussein is gone. Muammar Gaddafi is gone. The Afghan Taliban are gone. And then over time, we start to learn what the cost is: 4,400 Americans dead in Iraq. The Taliban back in power."

Himes said it's too soon to call the attacks on Iran’s nuclear facilities a success and cautioned against applauding them.

"But bottom line is we don't know, and if you look at the three conflicts I just mentioned, I would keep the optimism under the hat for a little while yet," he said.

Himes also said that he was "disturbed" by the fact that the strikes were undertaken without the approval of Congress, which he said holds the sole authority to declare war.

"There's not much ambiguity in the Constitution about who gets to approve these things," Himes said.