Iran's supreme leader Ayatollah Ali Khamenei on Wednesday rejected US calls for surrender in the face of blistering Israeli strikes and warned that any military involvement by the Americans would cause “irreparable damage” to them, in a recorded video aired by state TV.

It was the second public appearance by Khamenei since the Israeli strikes began, and came a day after U.S. President Donald Trump demanded “UNCONDITIONAL SURRENDER” in a social media post and warned Khamenei that the United States knows where he is but has no plans to kill him, “at least not for now.”

Trump initially distanced himself from Israel’s surprise attack on Friday that triggered the conflict, but in recent days has hinted at greater American involvement, saying he wants something “much bigger” than a ceasefire. The US has also sent more military aircraft and warships to the region.

Khamenei dismissed the “threatening and absurd statements” by Trump.

“Wise individuals who know Iran, its people, and its history never speak to this nation with the language of threats, because the Iranian nation is not one to surrender,” he said in the low-resolution video, his voice echoing. “Americans should know that any military involvement by the US will undoubtedly result in irreparable damage to them.”

Iran followed a similar sequence in releasing Khamenei’s statement before the video was aired, perhaps as a security measure. His location is not known and was impossible to discern from the tight shot that showed only beige curtains, an Iranian flag, and a portrait of Grand Ayatollah Ruhollah Khomeini, Khamenei's immediate predecessor who died in 1989.

Earlier in the day, an Iranian diplomat warned that US intervention would risk “all-out war.”

Foreign Ministry spokesman Esmail Baghaei did not elaborate, but thousands of American troops are based in nearby countries within range of Iran's weapons. The US has threatened a massive response to any attack.

Another Iranian official said the country would keep enriching uranium for peaceful purposes, apparently ruling out Trump's demands that Iran give up its disputed nuclear program.