Iran would have to acquire a nuclear weapon if attacked by the United States or its allies, an adviser to the country's supreme leader warned, following a threat by U.S. President Donald Trump.

The comments came after Iran's supreme leader, Ayatollah Ali Khamenei, promised to hit back if Trump carried out a threat to bomb the Islamic republic if it did not make a deal to curb its nuclear program.

China is ready to play a "constructive role" in ending the war in Ukraine but backs Russia in defending its "interests", top diplomat Wang Yi told Russian state news agency Ria Novosti in an interview published on Tuesday.

Donald Trump on Sunday repeated his suggestion he might seek a third term as president, which would defy the two-term limit stipulated in the U.S. Constitution.

Iran's supreme leader Ayatollah Ali Khamenei warned on Monday of a forceful retaliation if the Islamic republic is attacked, following a threat by U.S. President Donald Trump.

"They threaten to do mischief," Khamenei said of Trump's latest threat, during a speech on Eid al-Fitr, the holiday marking the end of the Muslim fasting month of Ramadan.

Residents scoured collapsed buildings Sunday searching for survivors as aftershocks rattled the devastated city of Mandalay, two days after a massive earthquake killed at least 1,700 people in Myanmar and at least 17 in neighboring Thailand.

The initial 7.7-magnitude quake struck near the central Myanmar city of Mandalay early Friday afternoon, followed minutes later by a 6.7-magnitude aftershock.

Iran has delivered a formal written response to U.S. President Donald Trump's letter proposing new nuclear talks and threatening consequences if a deal is not reached swiftly, Foreign Minister Abbas Araghchi said Thursday.

Trump gave Iran a two-month deadline to sign a new nuclear deal or face potential military action in his letter, sent three weeks ago.

A powerful earthquake centered in Myanmar has killed more than 1,000 people in the war-torn country and neighboring Thailand and caused widespread damage.

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Ukrainian President Volodymyr Zelensky on Thursday criticized "dangerous signals" on the possibility of lifting sanctions on Russia imposed over its invasion of Ukraine.

Russia and Ukraine on Thursday each accused the other of breaching commitments not to strike energy facilities, throwing yet more jeopardy on the prospects of even a temporary and partial halt in the three-year war.

The Trump administration is struggling to stem the fallout from revelations that top national security officials discussed sensitive attack plans over a messaging app and mistakenly added a journalist to the chain.

The White House said the information shared through the publicly available Signal app with Jeffrey Goldberg, editor-in-chief of The Atlantic magazine, was not classified, an assertion that Democrats said strains credulity considering that it detailed plans for an upcoming attack on Yemen's Houthis.