Trump’s mission impossible for allies: Reopening the Strait of Hormuz

President Trump has called on allied nations to reopen the Strait of Hormuz, to allow a fifth of the world’s oil to flow again through the passageway that Iran has effectively shut since the war started. The problem: Naval escorts for tankers through such a narrow waterway in a war zone would be nearly impossible, say allied officials and military experts. Reopening the strait would more likely come after a cease-fire and through international pressure on Iran, they say.

Forcing open the strait militarily is unrealistic, French President Emmanuel Macron said Thursday.

“It would take forever and would expose all those crossing the strait to risks” of Iranian attack, he said.

“Iran is trying to hold the global economy hostage in the Strait of Hormuz,” U.K. Foreign Secretary Yvette Cooper said Thursday after convening a meeting of more than 40 countries seeking to reopen the strait. They discussed political and diplomatic steps, including potential sanctions, she said. Military intervention wasn’t on the list of options discussed.

Trump said Wednesday that strikes on Iran would continue for more than two weeks. During that time, shippers are unlikely to risk sending commercial vessels through the combat zone, analysts say. The question is what level of assurance they need to start sailing again in large numbers.

U.S. and Israeli strikes have badly damaged Iran’s regular naval assets. Yet the main threat to shipping in the Strait of Hormuz comes not from Iran’s conventional navy but from its arsenal of land-based antiship missiles, drones, swarms of small attack craft, midget submarines and various types of mines. Geography complicates defending ships.

The strait is roughly 20 miles wide at its narrowest point and divided into lanes to separate marine traffic, forcing merchant ships to travel along predictable routes. The warning time of a potential attack, and the chance to respond, would be exceedingly brief. Iran has nearly 1,000 miles of coastline along the Persian Gulf, which it can use to launch attacks against ships, such as the drone strike that earlier this week struck a fully laden Kuwaiti oil tanker off the coast of Dubai.

The coastline is dominated by mountains and coves, allowing Iranian forces to launch surprise attacks with swarms of speed boats. Tunnels under the rock, or ones hidden by mangroves and in salt caves, shelter boats that can either be launched directly into the water, or from trailers. Qeshm Island is particularly problematic.

The largest island in the Persian Gulf, it shelters fast-attack craft, explosives-laden boats, drones and missiles belonging to the Islamic Revolutionary Guard Corps, the primary force responsible for securing the strait. Due to the short distances in the strait, Iran can cause significant damage even with short-range weapons, said Farzin Nadimi, senior fellow with the Washington Institute think tank. Fast-attack boats armed with rocket-propelled grenades can blow a hole in a ship’s hull, or mine the strait.

Such vessels can largely be deterred by the U.S. dominant air power, but “European powers will not be able, and probably not willing, to replace that capability,” Nadimi said. Military escorts, which shippers used in the Persian Gulf during the 1980-88 Iran-Iraq war, can only provide protection for a limited number of ships at a time. An estimated 30 million tons of cargo was damaged during that war.

In the Gulf of Aden, a multinational force provided protection against piracy with one warship for every dozen merchant ships, said Lars H. Bergqvist, a reserve officer in the Royal Swedish Navy and former United Nations military observer.

“The challenge isn’t just whether it can be done—it’s whether it can be done consistently and at the level of presence needed to reassure commercial traffic and deter interference,” said David Cattler, a former North Atlantic Treaty Organization assistant secretary-general for intelligence and a former U.S. Navy surface warfare and intelligence officer. Even cargo vessels under naval protection can be vulnerable. Commercial ships transiting the Red Sea under military escort have faced attacks from Houthi rebels in Yemen since 2024.

Iranian forces are potentially more dangerous, experts say.

As a result, shippers are likely to wait until fighting ceases and the international community acts. The first step in reopening the strait will likely be a U.N. resolution and a multinational force to oversee traffic, said Christian Bueger, a professor of political science at the University of Copenhagen who studies maritime security.

“It would be a military presence that could respond to incidents and reassure the shipping industry,” he said.

“The point is not to do escorts.” Such a mission in the strait would likely take a “layered approach,” drawing on lessons from the multinational mission formed in 2023 to respond to attacks by Yemeni Houthi rebels in the Red Sea, said Kevin Rowlands, a naval expert at the London-based Royal United Services Institute. Beginning with signals intelligence, and satellite and electronic surveillance of activity in the strait, such a mission would likely include maritime patrol aircraft and drones.

The ability to respond to incidents such as mine hits or missile attacks would require close communication between all involved nations and merchant ships, possibly carrying liaison officers onboard.

“The challenge isn’t naval,” Rowlands said.

“Putting a figure on how many warships is needed is not the right way to think about it. It’s about looking at how many layers of protection are needed.” A critical unknown is whether, if the U.S. and Israel stop striking Iran, Tehran will stop menacing ship traffic.

Iran has demanded reparations for destruction wrought in the five-week onslaught. If the U.S. and Israel don’t agree to payments, Iran may continue to impose a hefty toll on the world economy through its chokehold on the route for critical supplies of fuel, chemicals and fertilizer.

“It’s up to Iran to say that the war is over,” Rowlands said, cautioning that Iranian militia allies can threaten other chokepoints, such as the Bab al-Mandeb Strait off Yemen.

“Even if Iran decides that trade can flow through the strait, there might still be a risk that proxies take a different view,” he said. Write to Daniel Michaels at Dan.

Michaels@wsj.com and Sune Engel Rasmussen at sune.rasmussen@wsj.com