President Donald Trump was joking when he said the United States would declare the Strait of Hormuz a US territory after defeating Iran, a senior White House official told the Wall Street Journal, according to the newspaper.

The official said Trump had not discussed such a move with his advisers and was speaking in jest during a speech in New York on Friday. The comment nevertheless came amid an ongoing dispute between Washington and Tehran over control of the strategic waterway.

Trump told a gathering at a police academy on Long Island that, after the US finished defeating Iran, he would "pretty soon" declare the Strait of Hormuz a US territory.

"Essentially, that's what it is. We have the blockade. No ships get through unless we want them to," Trump said.

The White House clarification contrasts with the wording of Trump's remarks, which he followed by saying: "It's true." The seriousness of the proposal was not immediately clear after the speech.

Iran rejected the suggestion. Deputy Foreign Minister Kazem Gharibabadi said the strait would remain under Iranian authority and that Tehran would not be intimidated by US threats or displays of force.

The legal status of the waterway is more complicated than either side's political claims. The Strait of Hormuz is bordered by Iran and Oman, with jurisdiction over the waters divided between the two countries. The International Maritime Organization has described both states as having responsibility for managing the strait under international law.

The waterway has become a central point of confrontation during the US-Iran conflict. Reuters reported on Aug. 13 that shipping traffic had fallen to eight vessels on Tuesday, compared with 130 to 140 before the war, while Washington said it could maintain its naval blockade of Iran indefinitely.

The strait normally carries about a fifth of global oil and liquefied natural gas supplies, making disruption there a major concern for energy markets. Reuters reported that global oil supply forecasts had already been reduced as the conflict continued.

Trump has repeatedly claimed that the United States has "total control" over the waterway, while Iran has insisted that it will determine when and under what conditions commercial shipping can resume. The dispute remains unresolved despite continued diplomatic efforts.