For the second consecutive day, the Pentagon said it struck military sites in Iran on Wednesday night, hours after President Trump said he thought a three-week-old cease-fire between the two countries was “over.”
Iranian state media reported that explosions had been heard in at least three port cities along the country’s southeastern coast.
The latest strikes, the U.S. Central Command said, were intended to undermine Iran’s ability to threaten ships in the Strait of Hormuz, a critical waterway for global energy supplies that has become a central issue in the conflict.
Central Command called the attacks retaliation for “recent unjustified aggression against commercial shipping and civilian crews.”
Mr. Trump said earlier on Wednesday that while the United States would probably hit Iran “hard,” he did not expect a return to all-out war. “I don’t think it’s going to start again,” he told reporters at a NATO summit in Turkey. “I think it’s going to go very quickly.”
But later in the day, he said in a social media post that if Iran attacked ships again, “it will get much worse!”
Speaking aboard Air Force One while on his way back to the United States from the summit, the president maintained that Iran still wanted to make a deal despite the renewed and intense hostilities.
“They called a little while ago. They want to make a deal so badly,” he said. “I just don’t know if they’re worthy of making a deal. I don’t know that they’re going to honor the deal.”
The Iranians have said nothing about new negotiations.
Even before the strikes, the temporary truce in the four-month conflict between the United States and Iran had appeared on the brink of collapse, with each side accusing the other of repeatedly violating the terms of the agreement.
On Tuesday, the United States carried out airstrikes against more than 80 targets in Iran in retaliation for what the Pentagon said were Iranian strikes against three commercial ships, including a Saudi oil tanker and a Qatari vessel carrying liquefied natural gas.
The American strikes — about seven times the number the U.S. military launched in the round of retaliatory strikes in late June — targeted Iranian air defense systems, command and control networks, coastal radar sites, anti-ship missile capabilities and more than 60 Islamic Revolutionary Guards Corps small boats, Central Command said.
The strikes on Tuesday came hours after the Trump administration revoked a waiver allowing the sale of Iranian oil around the world.
Tehran has not claimed responsibility for the ship attacks. After the U.S. strikes and re-imposition of sanctions on oil sales, Iranian officials announced in a series of statements that the United States had violated the June 18 agreement intended to end the war.
Negotiations between Iran and the United States have been paused until after the multiday funeral ceremonies for Ayatollah Ali Khamenei, the supreme leader who was killed on the first day of the war.
Although the United States and Iran have agreed to restore access to the strait — with Mr. Trump declaring the waterway open to unrestricted navigation — the preliminary accord does not stipulate exactly how that should happen, and assigns to Iran the task of allowing the long-blocked traffic to get through. Iran has insisted that commercial ships sail near its shore, in a channel under Iran’s control, but many vessels are using American help to take a route near the Omani coast.
“What we’re seeing now is Iran, and more specifically the I.R.G.C., trying to exert control over the strait and declaring that this control is their sovereign right,” said Kevin Donegan, a retired Navy vice admiral who is a former top Navy commander in the Middle East.
“That’s the main card they have to play, and as a result we can expect they will continue to try to disrupt any ship traffic that uses routes different from the ones they have published,” Admiral Donegan said.
Erica L. Green contributed reporting.
