Amid escalating tensions between Israel and Iran, U.S. President Donald Trump on Monday (local time) urged civilians to "immediately evacuate Tehran," shortly after the White House announced he would be departing the G7 summit early to "attend to many important matters."

In a series of posts on his social media platform Truth Social, Trump strongly reiterated his long-held stance on Iran's nuclear ambitions, warning of serious consequences.

"Iran should have signed the 'deal' I told them to sign. What a shame, and waste of human life. Simply stated, IRAN CAN NOT HAVE A NUCLEAR WEAPON. I said it over and over again!" Trump wrote, urging immediate action as tensions rise. "Everyone should immediately evacuate Tehran!" he added.

In a follow-up post, Trump tied his firm stance on Iran's nuclear program to his broader political message, stating, "AMERICA FIRST means many GREAT things, including the fact that, IRAN CAN NOT HAVE A NUCLEAR WEAPON. MAKE AMERICA GREAT AGAIN!!!"

Israel has been conducting strikes in Tehran since Thursday night, but the U.S. has so far declined to join the operation. Shortly after Trump's post, Iranian media reported explosions and heavy air defense fire in Tehran. It's unclear if there was any relation between Trump's post and that attack.

It's not clear how many civilians have managed to evacuate, or whether such a mass exodus is even possible on such a short timetable.

Less than two hours before his Truth Social post, Trump said at the G7 summit in Canada that the U.S. was talking to the Iranians by phone and even suggested it will be "better to talk in person." Trump expressed hope that Iran would make a deal. "I think a deal will be signed. I think Iran is foolish not to sign one," he said.