The U.S. decision to strike Iran for the first time in a month shows Washington’s determination to win its cat-and-mouse contest for control over the Strait of Hormuz even at the risk of an escalation that could turn the conflict back into a hot war.
American forces said they hit Iranian launch sites that were preparing to fire rockets used to deploy naval mines in the narrow waters of the strait. In return, Tehran fired a salvo of missiles at Jordan, which is home to thousands of American troops. All were intercepted.
Iran’s grip on the Strait of Hormuz, which before the war was the gateway for a fifth of the world’s oil, has been a source of leverage for Tehran in the war and the talks to end it. The U.S. has waged a vigorous campaign to shake its hold and restore freedom of navigation.
At the heart of the fight is a fundamental imbalance of mine warfare. Iran doesn’t necessarily need to sink ships. It only needs to persuade shipowners, captains and insurers that the risk of encountering a mine while transiting the strait is too high to make the trip.
For the U.S., however, which wants to ensure safe passage, the mission is harder. It needs to disable or remove every mine.
Iran has exploited its geography and used dispersed, low-profile weapons as it seeks to seed mines and keep shipping at risk. The U.S. uses air and naval patrols and firepower in an effort to suppress threats as they emerge.
“So long as there is a track record of the strait being mined and of Iranians possessing large amounts of mines, it means shipowners will consider it too risky,” said Alessio Patalano, a professor of war and strategy at King’s College London.
Iran’s purported attempt to fire mines into the strait by rocket highlights the complexity of the U.S. effort to clear the vital waterway of the explosives and keep its shipping lanes open.
The American strike came days after President Trump said the U.S. had removed or detonated all mines in the waterway and warned that any vessel laying new ones would be destroyed.
Trump reimposed a naval blockade in mid-July, barring Iranian oil and other goods from entering and leaving its ports. The Navy, meanwhile, has been eating into Iran’s control of the strait by steadily shepherding tankers through the waterway.
Iran’s attempt to re-mine the strait indicates its frustration that the U.S. blockade has tilted the balance in the strait, said Eliot Cohen, a scholar at the Center for Strategic and International Studies think tank.
The geography of the strait magnifies the weapon’s impact. Commercial ships are concentrated into narrow lanes that constrict their ability to dodge mines and can make them easier to target.
Mines offer many advantages in modern naval warfare. They are relatively easy to acquire or make, and they are easy to move and deploy.
Militaries have, however, relied on mines for centuries. During the American Revolution, George Washington authorized an inventor to send explosive kegs against British shipping on the Delaware River, though the attack failed to hit its targets. In the 1850s, Russia made the first systematic defensive use of naval mines during the Crimean War, which the British countered with an early form of minesweeper.
By World War II, U.S. planes were able to lay more than 12,000 mines around Japan, sinking or badly damaging about 670 ships, according to the U.S. Navy Naval History and Heritage Command.
Part of the challenge for the U.S. today is the many tactics Iran can use to get mines into the water.
Iran’s regular navy has largely been destroyed but the Islamic Revolutionary Guard Corps still has large numbers of small, fast boats hidden along the coast that could drop mines.
Iran also has demonstrated a more unusual method: firing them into the sea from shore. During a naval exercise in 2025, the Revolutionary Guard demonstrated a system using a Fajr-5 rocket to deploy a sea mine at a distance.
Such a method could allow Iran to seed waters quickly without exposing a mine-laying vessel to U.S. forces. The U.S. hasn’t said whether the launchers struck Sunday were Fajr-5 systems, and details of the Iranian payload remained unclear.
Thomas Shugart, a naval consultant and former U.S. Navy officer, was surprised to hear of sea mines deployed from rocket launchers. Still, the size of the rockets suggests that any mines fired with them would likely be relatively small and simple, unlike the larger ones navies are accustomed to, he said.
The U.S. military nevertheless took them seriously enough to warrant destroying them, he said.
If Iran manages to lay more mines, then U.S. forces are left with the hard task of locating and clearing them.
Specialized naval vessels sweep wires through the water to cut the cables or chains that anchor mines to the seabed so they surface and can be destroyed, but that is dangerous in the contested waters of the strait. Alternatively, specially-equipped vessels, drones or aircraft mimic the magnetic fields, pressure or noise created by a passing ship to detonate the mines before they can do any harm.
U.S. Central Command said last week that American forces had cleared Iranian mines from the internationally recognized shipping lanes using Navy divers, Navy SEALs and American air power.
Such efforts will continue to be tested if the battle for the strait shifts from clearing a one-time minefield to keeping the same stretch of water continuously open. Some experts say no mine-clearance operation can guarantee every mine is gone.
“The most important point is that mine warfare is a game of unknowns,” said Scott Savitz, senior engineer at Rand and specialist in naval operations and technologies. “It’s never possible to say with complete certainty that all mines have been eliminated, only that the risk has been reduced to acceptable levels.”
Patalano said Iran’s proximity to the strait and the ability to disperse small boats, mines and other weapons along its coast make it difficult to eliminate the threat entirely. Even after a lane has been cleared, U.S. and allied forces have to prevent Iranian forces from slipping through and laying new mines.
“When you say it’s all demined, that’s only until the next time someone manages to slip through whatever measures that you put in place to control it and mine it again,” Patalano said.
Write to Georgi Kantchev at georgi.kantchev@wsj.com and Alistair MacDonald at Alistair.Macdonald@wsj.com