Iran vowed to “punish” the United States on Thursday after the American military said it had completed a “heavy wave of strikes” overnight, the latest retaliation for an attack by Tehran on U.S. forces in the Middle East.

The renewed fighting shattered a brief period of calm that had seen the two sides engage with a push to revive diplomatic efforts and stave off dramatic new escalation.

But President Donald Trump said the U.S. would hit the Islamic Republic hard after its attack on a base in Jordan. And the powerful Revolutionary Guard Corps (IRGC) signaled the flare-up would not end there, warning early Thursday that “the aggressor will be punished today” following the U.S. strikes.

There were also signs that the war was again expanding and drawing in new countries, raising the stakes for the region and the global economy.

After Saudi Arabia joined the U.S. in striking Iran-backed militants, Egypt confirmed Thursday that a drone ignited fires on two natural gas vessels at the port of Damietta.

It was not immediately clear who was behind the drone strike — on a U.S.-owned floating storage facility and a Greek-owned tanker — but an attack there by Iran would mark a significant new expansion of the conflict to a key U.S. ally and mediator. It would also highlight the broader risk to the world’s energy supplies from the difficulty in resolving the conflict.

Asked if it was Iran during an Oval Office event on Wednesday, Trump said he had been briefed on the incident and that “it’s a little more of the same.”

“It’s going to be straightening out,” he added, without expanding on what exactly he meant. “In the meantime, we’re going to be hitting them very hard because it’s our turn to hit them.”

Trump also vowed on Wednesday to “beat the f—ing s— out of” Iran after its Tuesday attack on American forces, according to Fox News, which cited a phone call with the president.