Three U.S. soldiers were killed in action and five others seriously injured as part of the military operation against Iran, the U.S. Central Command said Sunday.

Several others sustained minor shrapnel injuries and concussions, said the command in a statement on social media, adding that they are "in the process of being returned to duty."

"The situation is fluid, so out of respect for the families, we will withhold additional information," the command added.

Iran's three-member interim leadership council has been formed and begun its operations, Iranian President Masoud Pezeshkian said Sunday in a video message carried by state-run IRIB TV.

He made the announcement hours after Iran confirmed the death of the country's Supreme Leader Ali Khamenei in Saturday's U.S.-Israeli attacks on Iran.

Pezeshkian said the council will continue Khamenei's path with strength, vowing that Iran's armed forces are ready to "smash" the bases of the "enemies."

U.S. President Donald Trump said on Sunday the U.S. forces have sunk nine Iranian warships and largely destroyed Iran's navy headquarters.

"I have just been informed that we have destroyed and sunk 9 Iranian Naval Ships, some of them relatively large and important," Trump said in a post on Truth Social.

"In a different attack, we largely destroyed their Naval Headquarters," Trump said, adding that the U.S. military is going after the rest of the Iranian navy's fleet.

The military strike against Iran will "take four weeks -- or less," U.S. President Donald Trump said in an exclusive phone interview with Britain's Daily Mail, the newspaper reported Sunday.

The Daily Mail said Trump "broke his silence" on the first U.S. casualties in the conflict. Three U.S. soldiers were killed in action and five others seriously injured as part of the military operation against Iran, the U.S. Central Command said Sunday.

Trump acknowledged the deaths were the first casualties of his second term, the report said.

The European Union (EU) is following developments in Iran and the broader Middle East "with utmost concern" and has called on all sides to exercise maximum restraint, EU foreign policy chief Kaja Kallas said on Sunday in a statement issued on behalf of the bloc.

The statement called for maximum restraint, the protection of civilians and full respect for international law, including the principles of the United Nations Charter and international humanitarian law, warning that the Middle East "stands to lose greatly from any drawn-out war."

The EU said it would continue contributing to diplomatic efforts to reduce tensions and seek a lasting solution to prevent Iran from acquiring a nuclear weapon. It stressed the importance of Iran's full cooperation with the International Atomic Energy Agency and compliance with its legal obligations under the Nuclear Non-Proliferation Treaty and the Comprehensive Safeguards Agreement.