TEHRAN, Iran (AP) — Iran struck back at the United States early Wednesday for killing its most powerful military commander, firing a barrage of ballistic missiles at two Iraqi military bases that house American troops in what the Iranian supreme leader said was a “slap” against the U.S. military presence in the region.

The dramatic blast of more than a dozen missiles caused no casualties, however, and U.S. President Donald Trump said hours later that Iran “appears to be standing down.

It was a signal that both sides were stepping away from an immediate spiral of more direct exchanges that could throw the Middle East into great turmoil.

Speaking at the White House, Trump said the U.S. would impose new “punishing economic sanctions” on Iran to force it to stop its nuclear program and what he called its “hostilities” in the region. But he also said Washington was open to a deal with Tehran.