The United States military launched a blockade of Iranian ports and the Strait of Hormuz on Monday after weekend peace talks between Washington and Tehran, held in Pakistan, ended without an agreement. U.S. Central Command announced the measure would take effect at 10 a.m. Eastern Time (1400 GMT) on April 13, targeting all maritime traffic entering or departing Iranian ports and coastal areas across the Arabian Gulf and Gulf of Oman. The blockade does not apply to vessels transiting the strait between non-Iranian ports, the command stated, indicating an effort to limit — rather than fully close — one of the world's most critical shipping lanes.

The Strait of Hormuz, a narrow waterway between Iran and the Arabian Peninsula, is the passage through which roughly one-fifth of the global oil supply flows. Its status has been a central flashpoint in the broader U.S.-Israel war on Iran, which has already removed an estimated 10 million barrels per day from global supply since hostilities began in late February. One of the key sticking points in the collapsed weekend negotiations was Iran's reported proposal to charge vessels up to $2 million per transit — a plan rejected by Trump and other world leaders as incompatible with internationally recognised freedom of navigation principles. Iran's Revolutionary Guard warned that any approaching military vessels near the strait would constitute a violation of the existing ceasefire, and Iran's parliament speaker, who led the Pakistani talks, said Tehran would not capitulate to U.S. pressure.

Markets reacted sharply to the announcement. Brent crude — the international oil benchmark — surged more than 7% to above $102 a barrel, having already climbed from around $70 before the conflict began. U.S. West Texas Intermediate crude rose 8.6% to nearly $105. Grain futures also moved higher, with wheat, corn and soybean prices climbing on fears that disruptions to fuel and fertiliser supply chains could ripple through global food markets. Shipping data showed oil tankers had already begun steering clear of the strait, and tracking firm Lloyd's List Intelligence reported that all traffic through the waterway had stopped following Trump's announcement.

Military analysts caution that enforcing the blockade will be far from straightforward. Former senior Pentagon official Dana Stroul described the mission as