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.

China poses the top threat to American interests and security globally and is making "steady" progress towards having the ability to seize the self-ruled island of Taiwan, an annual US intelligence report warned Tuesday.

In a matter of days, U.S. President Donald Trump has extended a hand to Iran and bombed Tehran's allies in Yemen. His administration has both demanded that Iran dismantle its nuclear program and offered more flexibility.

U.S. President Donald Trump has downplayed the texting of sensitive plans for a military strike against Yemen's Houthis this month to a group chat that included a journalist, saying it was "the only glitch in two months" of his administration as Democratic lawmakers heaped criticism on the administration for handling highly sensitive information carelessly.

Trump told NBC News that the lapse "turned out not to be a serious one," and expressed his continued support for national security adviser Mike Waltz.