How a US blockade near the Strait of Hormuz could work
President Donald Trump said a blockade of Iranian ports began Monday after talks to further a fragile ceasefire ended without a deal, setting off questions about how the United States would enforce restrictions near the Strait of Hormuz and what effects the pressure tactic could have on global prices. The reporting said Iran had previously halted nearly all tanker traffic through the key waterway, allowing only some ships viewed as friendly while charging fees.
Experts told The Associated Press that enforcing a blockade would likely demand sustained resources from the U.S. Navy and careful administration. They said American military officials had offered few details on how the blockade would operate in practice, including where warships would be positioned and what rules would be applied to ships seeking to transit.
One defense official said the U.S. has 16 warships in the Middle East, while another said there were no warships in the Persian Gulf itself; both spoke on condition of anonymity to discuss sensitive military operations. The second official pointed to a notice to mariners that, according to the report, says access to Iranian ports is being restricted but that the ways the measures would be applied “will be applied in practice … are in development.”
Sidharth Kaushal, a naval power expert at the Royal United Services Institute, said the Strait of Hormuz poses a major challenge because of the sheer amount of shipping that typically transits the narrow waterway. He said “a lot depends on the early days of the blockade,” including how many vessels the U.S. can seize and whether it convinces ships attempting to slip through that they will be seized, adding, “in all likelihood, I’d say it will prove difficult for the U.S. to enforce.” Todd Huntley, director of Georgetown University Law Center’s National Security Law Program, said the strait’s narrow geography limits the area of concern, but that “is going to be a challenge” given the traffic.
International law questions also hinge on enforcement details, particularly humanitarian access. Huntley said the U.S. may have to consider whether to allow humanitarian aid to reach Iranian ports, because that decision could shape whether the blockade is lawful under international law. He said international rules require blockade-enforcing nations to act impartially and to issue an advisory to mariners, and he framed the issue as a matter of method, saying, “How it is carried out will determine whether it is lawful or not.”
Huntley, a retired Navy captain and judge advocate general, said a blockade can’t be carried out with the goal of starving the civilian population, citing the DOD law of war manual’s approach to relief supplies. He added, “You can’t enact a blockade with the goal of starving the civilian population,” and said the manual states neutral vessels carrying relief supplies should be allowed to pass.
Raul Pedrozo, a professor of international law at the Naval War College, said few merchant vessels were likely to try to evade the blockade because they would not want to risk confrontation with the U.S. Navy, telling the Associated Press, “They see a warship, and they’re going to heave to.”
Experts also said blockades are not a guaranteed end to conflict, even if they can exert pressure. Kaushal said there are ways countries can adjust by economizing, importing substitutes, or giving up certain goods, and that “it can make things a lot harder in a lot of ways, but it doesn’t necessarily achieve decisive outcomes.” Farzin Nadimi of the Washington Institute for Near East Policy said the blockade could also provoke an Iranian response, including naval mines, fast-attack boats and missiles, and he argued the operation may not stay limited in duration, saying, “The U.S. wants this to be a short and sweet operation. I don’t think that it can be.”
In the report, Nadimi’s warning came alongside the account that Trump said Iran has some “fast attack ships” remaining and threatened that any vessels that come “anywhere close” to the U.S. blockade would be destroyed by a “quick and brutal” strike. The report said Iran responded with its own threats on ports in the Persian Gulf and the Gulf of Oman.
Oil prices could keep rising as the blockade uncertainty affects shipping and markets, experts said. Vidya Mani, a visiting associate professor at Cornell University whose research focuses on supply chains, said “the problem with a two-side blockade” is that it could take longer for the strait to open and for an agreement to be reached, which would send prices higher, saying it’s “what’s going to send these prices further skyrocketing.” The report said crude was trading Monday above $100 a barrel, up from roughly $70 before the war.
The Associated Press reported that households and businesses were already seeing the effects, including gas prices rising to an average of more than $4.12 a gallon, compared with $2.98 before the war. It also said Asian countries could feel additional strain because they rely more heavily on fuel imports from the Middle East, while emphasizing that oil is globally traded and consumers worldwide would feel the impact.
Beyond energy, analysts said blockade restrictions could disrupt shipping of items including food and fertilizer. Patrick Penfield, professor of supply chain practice at Syracuse University, said the United Arab Emirates, Qatar and Bahrain could see “dramatic food price increases” because supplies would have to be flown in, and he said some 30% of the world’s fertilizer comes through the strait, potentially harming farmers and worsening hunger. Mani told the report that chemicals used to make basic supplies and materials such as aluminum also pass through the region, and she warned that price pressures can persist across successive crises, saying, “We just have to be prepared for constant higher prices, irrespective of how this blockade turns out,” and “Each crisis has a lingering effect on the next one.”
The report said Associated Press writers Konstantin Toropin in Washington and Mae Anderson in New York contributed.