TEHRAN / WASHINGTON — Iran's Islamic Revolutionary Guard Corps Navy announced Friday that the Strait of Hormuz — the narrow chokepoint through which roughly 20 percent of the world's oil supply passes every single day — is closed until further notice. A tanker was also reportedly attacked by Iranian gunboats while transiting the strait, underscoring that Tehran means business this time.
Oil markets, which had already been jittery, did not take the news well. Brent crude jumped sharply on the announcement as traders began doing the math on what a sustained closure would mean for global supply chains that have never really built a workaround for the one waterway that most of the Persian Gulf's oil has to pass through.
The closure was framed by Iranian officials as retaliation for what they called an unlawful blockade of Iranian interests — language that aligns with ongoing tensions over U.S. and Israeli pressure campaigns targeting Iran's oil exports and nuclear program. The IRGC Navy has a long history of threatening Hormuz closures, but has rarely followed through with anything sustained.
The United States Navy's Fifth Fleet, headquartered in Bahrain and specifically tasked with keeping regional waterways open, said it was monitoring the situation and conducting operations in the area. Translation: American warships are already moving.
Saudi Arabia, which exports the majority of its oil through the strait, convened an emergency cabinet session. The UAE issued a statement calling on all parties to de-escalate. Neither country has much leverage over what happens next.
Shipping insurers — a group not known for drama — responded by sharply raising premiums for vessels transiting the region. Several major carriers announced they were rerouting ships around the Cape of Good Hope, adding two weeks to delivery times and significant costs.
How long the closure holds is anyone's guess. Iran has blinked before. But with tensions at a recent high and a tanker already attacked, the window for a quick, quiet resolution appears narrow.