US blockade of Iran will be major military endeavour, experts say
"Trump wants a quick fix. The reality is, this mission is difficult to execute alone and likely unsustainable over the medium to long-term," says a former senior Pentagon official.
President Donald Trump arrives to speak about the Iran war from the Cross Hall of the White House on Apr 1, 2026, in Washington. (File photo: Reuters/Alex Brandon)
WASHINGTON: 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 over the weekend in Islamabad, said the US Navy "will begin the process of BLOCKADING any and all Ships trying to enter, or leave, the Strait of Hormuz".
The US 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 (Apr 13) at 10am in Washington (10pm, Singapore time), CENTCOM said.
Trump also said US 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 per cent 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.
Simon Frankel Pratt, senior lecturer in political science at the University of Melbourne, told CNA’s Asia First that the move is “certainly feasible”, given the US has the naval capability to carry it out.
However, he said it remains unclear whether Washington will target only Iranian ports or extend the blockade to all vessels that have complied with Tehran’s toll system.
The blockade could “go some way to restoring US leverage”, he said, particularly if the aim is to stop Iran from establishing a toll regime.
But he warned it would likely worsen the energy and economic crisis in the short term, while also costing the US diplomatic capital among partners affected by the disruption.
He added that the move could raise legal and political questions, noting that a blockade would be difficult to justify under international law and could further strain ties with countries that rely on the waterway.
Even so, he said it may be “the least bad option available” after negotiations collapsed.
"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 US military has not offered basic details yet about the blockade, including how many US 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 US 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 US partners such as India or South Korea?
And what would Iran do? Retired Admiral Gary Roughead, a former chief of US naval operations, cautioned that Iran could fire on ships in the Gulf or attack infrastructure of the Gulf states that host US 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 per cent since the US and Israel launched the war on Feb 28.
Trump said on Sunday that the price of oil and gasoline may remain high in the United States through November's US midterm elections, which could see Trump's Republicans lose control of the US 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 US strikes inside Iran, citing missile factories as one possibility.
US Senator Mark Warner of Virginia, the ranking Democrat on the Senate Intelligence Committee, questioned the strategy, noting Iran could send speedboats to mine 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 US 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.
Stephen Zunes, director of Middle Eastern studies and professor of politics at the University of San Francisco, told CNA938 that the blockade risks backfiring and could deepen the crisis rather than resolve it.
He warned that the move could expose US forces to further attacks and make an already fragile situation “far worse”.
He said such pressure is unlikely to force Iran to give in, arguing instead that it could harden Tehran’s position and reduce the chances of a negotiated outcome.
Zunes also pointed to the failed talks, saying earlier US demands for Iran to fully give up its nuclear programme were unrealistic and contributed to the breakdown.
He said a more gradual approach – such as securing a temporary reopening of the strait first – might have had a better chance of success.
He added that the broader impact could be significant, with countries in Asia that depend on Gulf energy flows likely to feel the strain if tensions escalate further.
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.
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