In the days before President Trump signed his preliminary deal with Iran after a dinner at Versailles — where World War I officially ended — he and his aides described their strategy: The Strait of Hormuz would open to traffic, and the United States would open the spigot so that Iran could sell billions of dollars of oil.

The theory, Mr. Trump said, is that after years of sanctions, Iran would quickly get addicted to a torrent of revenue, and access to dollars in Western banks. It was a “really good deal for Iran,” the president said in a call to a New York Times reporter three days before he signed the June 17 memorandum of understanding.

“They are actually proud of it,” he said of the Iranian negotiators. “I think they were tired of getting hit.”

Apparently not. Less than a month into the accord, strikes on three ships passing through the strait, in a channel beyond Iran’s control, led Mr. Trump to revoke the waiver that allowed Iran to sell oil. The United States has bombed more than 170 Iranian military targets over two nights. And no negotiations are scheduled, at least for now, on the far larger, more complex and ostensibly permanent agreement that the two sides had agreed to negotiate in 60 days.

If Mr. Trump and his aides now have a Plan C — after bombing and a preliminary accord failed — they have not described it. Instead, it appears that they are returning to the oil sanctions and bombing runs that Mr. Trump describes as devastating, but that so far have only led to the current tangle.

“So, the deal is very simple,” Vice President JD Vance said on Wednesday. “If they shoot at ships, we’re going to knock the hell out of them,” added the vice president, who opposed the initial Feb. 28 attack but has since been tasked with defending the war and negotiating a way out of it.