George Clooney drew the ire of the White House this week after deeming President Donald Trump’s public rhetoric on Iran a “war crime.”

Trump wrote on his Truth Social platform early Tuesday that “a whole civilization will die” if no deal between the U.S. and Iran could be reached by that evening. A two-week ceasefire between the two nations was agreed upon later that day, though foreign policy experts say its specifics are highly questionable.

Clooney, a longtime critic of Trump and the GOP at large, condemned the president’s threats while speaking at a Wednesday event for about 3,000 high school students in Italy, organized by the Clooney Foundation for Justice.

“Some say Donald Trump is fine. But if anyone says he wants to end a civilization, that’s a war crime,” he said, per Variety. “You can still support the conservative point of view, but there must be a line of decency, and we must not cross it.”

It didn’t take long for White House Communications Director Steven Cheung to clap back at Clooney’s remarks.