US President Donald Trump demanded Iran's "unconditional surrender" on Friday, a dramatic escalation of his demands a week into the war he launched alongside Israel. Trump made the remarks on social media just hours after Iran's president announced that unspecified countries had begun mediation efforts in one of the first signals of any diplomatic initiative to end the conflict.

"There will be no deal with Iran except unconditional surrender!" Trump wrote. "After that, and the selection of a great & acceptable leader(s), we, and many of our wonderful and very brave allies and partners, will work tirelessly to bring Iran back from the brink of destruction, making it economically bigger, better, and stronger than ever before."

On Thursday, Trump had told Reuters in a telephone interviewthat he was demanding the right to help select Iran's new supreme leader, to replace Ayatollah Ali Khamenei, who was killed on the first day of the war.

Israel pounded the Lebanese capital, Beirut, on Friday after ordering an unprecedented evacuation of the entire southern suburbs of the city, in a major expansion of the war.

It also launched a new wave of attacks on Iran, saying 50 of its warplanes had struck a bunker beneath the destroyed Tehran compound of Khamenei, still being used by Iran's leadership after he was killed.

Iran's President Masoud Pezeshkian posted on X: "Some countries have begun mediation efforts." He did not identify the countries or provide further details.

"Let's be clear: we are committed to lasting peace in the region, but we have not the slightest hesitation in defending the dignity and authority of our country. Mediation should address those who underestimated the Iranian people and ignited this conflict," he added.

Under Iran's system, the president is subordinate to the supreme leader, but Pezeshkian is now serving on a panel that has assumed Khamenei's duties.