President Trump on Monday warned that those in Tehran should “immediately evacuate” as he lamented Iran’s decision not to sign an agreement with the United States limiting its nuclear program.

“Iran should have signed the ‘deal’ I told them to sign. What a shame, and waste of human life,” Trump posted on Truth Social. “Simply stated, IRAN CAN NOT HAVE A NUCLEAR WEAPON. I said it over and over again! Everyone should immediately evacuate Tehran!”

Trump’s warnings echo those earlier in the day from Israeli officials, who urged hundreds of thousands of people in the Iranian capital to evacuate ahead of strikes in its escalating military campaign against Iran. Tehran has a population of nearly 10 million people.

The president’s post could also be seen as something of a tacit endorsement of Israel’s increasingly aggressive campaign to go after Iran. It marks a shift in tone from just days ago, when the president had indicated Iran may have a “second chance” to come to the negotiating table.

Israeli Prime Minister Benjamin Netanyahu earlier in the day declined to rule out targeting Iran’s supreme leader, something Trump had reportedly cautioned him against doing. Israeli forces have also said they have damaged Iran’s air defense systems, giving Israel air superiority and the ability to essentially strike at will.

“The ‘forever war’ is what Iran wants, and they’re bringing us to the brink of nuclear war,” Netanyahu told ABC News. “In fact, what Israel is doing is preventing this, bringing an end to this aggression, and we can only do so by standing up to the forces of evil.”

Israel and Iran exchanged strikes for the fourth consecutive day Monday. The conflict broke out last week when Israeli missile strikes targeted Iranian nuclear facilities and killed multiple top military leaders.

Trump has been peppered with questions in the days since about potential U.S. involvement in the conflict. While the Trump administration said Israel’s initial strikes were a unilateral action, the U.S. assisted Israel in intercepting retaliatory strikes from Iran last Friday.

Trump sidestepped a question earlier Monday on what it would take for the U.S. military to get involved.

“I don’t want to talk about that,” he told reporters on his first day of the Group of Seven summit in Alberta, Canada.

Updated at 4:06 p.m. EDT