Between March 7 and March 11, 2026, maritime analytics firm Windward counted just 10 commercial vessel crossings of the Strait of Hormuz. A normal day sees 70 to 80. The collapse in traffic followed large-scale strikes involving Iran, the United States and Israel, an escalation Windward refers to as Operation Epic Fury.
Many of the ships that kept moving were Iranian-flagged or tied to higher-risk operators, among them sanctioned and shadow fleet vessels, the firm said.
A corridor a few miles wide
The strait links the Persian Gulf with the Gulf of Oman and the Arabian Sea. Iran lies to the north, Oman and the United Arab Emirates to the south. At its narrowest the water is about 20 miles (32 kilometers) across, and the lanes ships actually use are much tighter: two miles wide in each direction, with a buffer zone between them. The International Maritime Organization adopted that traffic separation scheme in 1973 and revised it in 1979.
Roughly 20 million barrels of oil pass through every day, about a fifth of global oil demand, according to Windward. Saudi Arabia, Iraq, Kuwait, the UAE and Qatar all ship through it. Almost 90% of the volumes exported that way were bound for Asia. Qatar, which exported over 112 bcm of liquefied natural gas in 2025, has no other route for its LNG to market.
A long record of confrontation
Control of the strait has been contested for centuries. Portuguese forces took the island of Hormuz in the early sixteenth century and built a fortress and customs station to tax passing ships. An alliance of the Safavid Persian Empire and the English East India Company pushed them out in 1622.
In the Iran-Iraq War, from 1980 to 1988, both countries attacked commercial shipping in what became known as the Tanker War. Iraq began hitting vessels bound for Iranian ports in 1981, using aircraft and anti-ship missiles such as Exocets. Iran answered in 1984 with improvised attacks on ships linked to Iraq’s trading partners. The United States and other nations sent warships to escort vessels through the Gulf.
Sanctions over Iran’s nuclear program brought repeated threats to close the strait through the 2000s and early 2010s. It was never fully blocked, but Western and regional navies deployed in force.
Iranian patrol boats fired warning shots and seized the Marshall Islands-flagged container ship Maersk Tigris in April 2015. Iran tied the seizure to a legal dispute, and the ship was later released. In July 2019, Iran detained the British-flagged tanker Stena Impero shortly after UK authorities seized an Iranian tanker near Gibraltar. The U.S. Navy’s Fifth Fleet says Iran has “harassed, attacked, or seized” multiple internationally flagged merchant vessels in the region in recent years.
What happened in 2026
Windward recorded more than 20 confirmed incidents involving commercial vessels and offshore assets early in the conflict. The ships named include Skylight, MKD Vyom, Stena Imperative and Athe Nova. Iranian forces threatened to target vessels and offshore infrastructure in and around the strait.
Electronic interference spread too. On March 7 alone, GPS and AIS disruption hit more than 1,650 vessels across the Gulf, and some showed up falsely positioned anywhere from Kuwait to Oman. Windward found at least 30 jamming clusters spanning Saudi Arabia, Kuwait, the UAE, Qatar, Oman and Iran.
Some crews responded by typing their ownership into AIS destination fields, with messages such as “CHINESE CREW OWNER” or “IRAQI OWNER.” Windward identified 36 vessels doing this, mostly cargo ships and tankers under Panama, Liberia and Hong Kong flags.
The firm’s conclusion is that the strait does not have to be sealed to hurt trade. Targeted attacks, jamming and thinner traffic were enough to raise costs and unsettle energy supply chains.
