The last time the world seriously worried about the Strait of Hormuz going dark, it was a threat. This time, Iran’s Islamic Revolutionary Guard Corps is making it a policy.

IRGC spokesperson Ali Mohammad Naini declared that no oil would leave the Gulf bound for the US or its allies until conditions changed.

What happened and why it matters

The Strait of Hormuz closed around March 4, 2026. To understand why that is a five-alarm problem, consider what passes through that narrow chokepoint: roughly one-fifth of the world’s daily oil supply, along with significant volumes of liquefied natural gas.

Brent Crude surged past $120 per barrel almost immediately.

The IRGC followed through with direct attacks on commercial shipping vessels in the region, recording incidents on June 25, June 27, July 6, and July 7.

The US responded by revoking General License X on July 7. That license, originally issued on June 22, had permitted limited Iranian oil sales under a narrow carve-out. Washington pulled it one week after IRGC vessel attacks resumed.

The IRGC then escalated further, threatening US military and infrastructure sites across the region following attacks on Iranian tankers.

The broader energy market fallout

For energy companies, insurance costs for vessels operating anywhere near the Gulf have jumped sharply, and some shipping firms have already begun rerouting away from the region entirely. Rerouting around the Cape of Good Hope adds roughly two weeks to transit times and significant costs, which feeds back into the price of everything those ships carry.

LNG markets face their own version of this problem. Qatar, one of the world’s largest LNG exporters, ships through the Strait of Hormuz. Any sustained disruption to LNG flows tightens an already-strained European energy market still working through the aftereffects of reduced Russian pipeline supply.

What investors should watch now

The immediate oil price move is already in the market. What comes next depends on three variables: whether US naval forces can reopen or protect shipping lanes, whether diplomatic back-channels produce any de-escalation, and whether IRGC attacks on commercial vessels continue or intensify.

Currency markets are already adjusting. The Japanese yen, Korean won, and Indian rupee are all vulnerable to sustained high oil prices given those economies’ import dependence.