US President Donald Trump | Photo Credit: EVELYN HOCKSTEIN

A US naval blockade of Iran ​is a major, open-ended military endeavour that could trigger fresh retaliation from Tehran and put tremendous strain on an already fragile ceasefire, experts say.

President ‌Donald Trump, in a social media post after no deal emerged from peace talks this weekend in ​Islamabad, said the U.S. Navy "will begin the process of BLOCKADING any and all Ships trying to enter, or ⁠leave, the Strait of Hormuz."

The U.S. military's Central Command later said the blockade will only apply to ships going to or from Iran, including all Iranian ports on the Arabian Gulf and Gulf of Oman. It will take effect on Monday at 10 a.m. in Washington (1400 GMT), CENTCOM ‌said. Trump also said U.S. forces would interdict vessels that have paid tolls to Iran, even if those ships are now in international waters. "No one who pays an illegal toll will have safe passage on the high seas," ‌Trump wrote on Truth Social.

The ultimate goal, Trump said, would be to pressure Iran to end its effective closure ‌of ⁠the strait, a choke point for about 20% of the world's oil, to all but the countries that ⁠secure safe passage from Tehran.

If Trump's strategy succeeds, he would eliminate Iran's greatest point of leverage in negotiations with the United States and clear the strait again for global trade, potentially lowering oil prices. But a blockade, experts say, is an act of war that requires an open-ended commitment of a significant number of warships.

"Trump ​wants a quick fix. The reality is, this ‌mission is difficult to execute alone and likely unsustainable over the medium to long-term," said Dana Stroul, a former senior Pentagon official during the Biden administration now at The Washington Institute for Near East Policy.

IRANIAN RETALIATION

The U.S. military has not offered basic details yet about the blockade, including how many U.S. warships will enforce it, whether warplanes will be used and whether any ‌Gulf allies will assist in the effort. Central Command declined to respond to requests for comment.

With enough warships, the ​U.S. Navy could set up a blockade that intimidates many commercial tankers from trying to power through with Iranian oil, experts say.

But would the United States be prepared to board and seize — or even damage ⁠or sink — ships that try to break the blockade? What if they carry oil for China, a major power, or U.S. partners such as India or South Korea?

And what would Iran do? Retired Admiral Gary Roughead, a former chief of U.S. naval operations, cautioned that ‌Iran could fire on ships in the Gulf or attack infrastructure of the Gulf states that host U.S. forces.

"I honestly believe that if we begin to do it, that Iran will have some kind of a reaction," Roughead said. Iran's threats to shipping have caused global oil prices to skyrocket about 50% since the U.S. and Israel launched the war on February 28. Trump said on Sunday that the price of oil and gasoline may remain high in the United States through November's U.S. midterm elections, which could see Trump's Republicans lose control of the U.S. Congress if there is a public backlash. The war has already been unpopular.

GAS PRICE PROBLEM

Frustrated ‌by Iran's refusal to end the war on his terms, Trump on Sunday also floated the possibility of a resumption of U.S. strikes inside Iran, citing ​missile factories as one possibility.

U.S. Senator Mark Warner of Virginia, the ranking Democrat on the Senate Intelligence Committee, questioned the strategy, noting Iran could send speedboats tomine the strait or put bombs against tankers.

"How is that going ⁠to ever bring down gas prices?" Warner asked on CBS's "Face the Nation."

Thousands of U.S. military strikes have severely weakened Iran's military. But analysts ⁠say Tehran has emerged from the conflict as a vexing problem for Washington, with a more hardline leadership and a buried stockpile of highly enriched uranium.

Trump threatened on Sunday that "any Iranian who fires at us, or at peaceful vessels, ‌will be BLOWN TO HELL!"

Iran's Revolutionary Guards responded with a statement warning that military vessels approaching the strait will be considered a ceasefire breach and dealt with harshly and decisively, underlining the risk of a dangerous escalation.

Stroul said the crisis will ​require a long-term, international effort to resolve.

"Over the long run, this will need to be resolved through diplomacy and international political will," she said.

Published on April 13, 2026