"We're taking over the strait. They've got nothing," Trump said in a phone interview with Fox News.
Trump said the United States would assume responsibility for protecting shipping through the strait and expected other Middle Eastern countries to pay for the mission.
"And we're going to keep the strait, and we'll probably run it. We'll become the guardian of the strait. Maybe we'll call it the 'guardian angel of the strait.' And we should be reimbursed for that. When we do that, we're going to be reimbursed because the other nations are very wealthy, they're on our side."
He later elaborated on the proposal in a Truth Social post, saying Washington would restore a blockade targeting Iranian shipping while allowing all other commercial traffic to pass.
"The Hormuz strait is open, and will remain open, with or without Iran. We are reinstating the Iranian blockade, so named because it is only stopping Iran's ships or customers from entering or leaving. All other countries will have fair and open use of the strait," he said.
"The U.S.A. will be, from this point forward, known as 'the guardian of the Hormuz strait,'" Trump added.
He also said the United States would charge countries using the waterway a fee equal to 20% of the value of cargo shipped to cover "any and all costs necessary to do the job of providing safety and security to this very volatile section of the World." It was not immediately clear whether US allies had agreed to such an arrangement.
Trump said his administration had believed it had reached a lasting understanding with Tehran before deciding Iran had violated it.
"What nobody knows, we had a deal. It was a done deal, and then they broke it. They always break it. We've had 10 deals with these people, and so we're just going to hit them very hard."
The remarks came after the United States carried out another round of strikes against Iran following Iranian attacks on US facilities across the Persian Gulf and Tehran's renewed declaration that the Strait of Hormuz was closed.
The exchange has effectively collapsed the interim memorandum of understanding reached in June, which had aimed to reopen the waterway and provide a framework for further negotiations.
Iran says it charges less
Iranian Foreign Minister Abbas Araghchi rejected Trump's statement that Washington would become the strait's guardian.
"POTUS is absolutely right. Whoever provides secure and safe passage of commercial vessels through the Strait of Hormuz should be compensated for this service," he said. "Iran has always been the guardian of the Strait and will remain so forever. 20% is of course too much. We will be fair."
New attacks on nuclear sites
Trump also said on Monday that Iran's Pickaxe Mountain nuclear site could soon become a US target.
Speaking to conservative radio host Hugh Hewitt, Trump said the United States was closely monitoring the deeply buried facility.
"A nice big fat shot right in the front door," Trump said, adding the United States would "probably give Pickaxe a shot relatively soon."
Trump also indicated further military action was imminent.
"It was a test. We didn't know," he said of the memorandum of understanding with Iran. "Memorandums of understanding, when you're dealing with sleazebags, don't mean much. It was sort of a test, and they weren't there. They didn't honor the test."
The renewed campaign has also reignited opposition in Congress.
Democratic Senator Adam Schiff said he would introduce a new War Powers Resolution this week to force another Senate vote on ending US military involvement in Iran, while Senate Democratic leader Chuck Schumer said Trump's "so-called understanding" with Iran had collapsed.
"Enough is enough. End the war," Schumer wrote on X.
Critics from both parties also argued the administration was stretching its legal authority. "The president can't just wish away months of war he said would last only four to six weeks," a senior Democratic aide in the House of Representatives told Reuters.
Meanwhile, the US military operation has continued alongside Trump's remarks. US Central Command said American forces have struck more than 300 Iranian military targets over the past week and announced additional attacks on Monday.
"These strikes will continue imposing a heavy cost on Iranian forces and degrade their ability to attack innocent civilians and commercial shipping in the Strait of Hormuz," CENTCOM said.
