Iran announced on 25 June 2026 that ships in the Strait of Hormuz must use routes it has designated, or face danger. According to IRNA, the warning puts responsibility directly on ship captains and their insurance companies to comply.

Iran claims it has the right to make these rules because the Strait borders its coast. It made this argument to the United Nations in April 2026, calling a proposal for open shipping unlawful and politically motivated. The US, Britain, and most other countries disagree—they say the Strait is an international waterway where ships can pass freely. But Iran is now backing up its legal claim with real action: designated routes and the threat of force.

Iran has been firing on ships. US officials told Reuters that Iran attacked a cargo vessel in the Strait with a missile. In April 2026, a Greek-owned ship called the MSC-Francesca was hit in the same waters. The pattern is clear: Iran makes a legal demand, sets up routes, then attacks ships that do not follow them. The June announcement is the latest step.

Why This Route Decision Matters

The Strait of Hormuz is where roughly one-fifth of the world's oil passes through. Tankers and ships carrying liquefied natural gas (LNG) squeeze through a channel only 33 nautical miles wide at its narrowest point. Iran says it controls part of this, so it can decide which ships go where. Other countries say the Strait is international territory where anyone can sail. Iran is not trying to win this argument in court. Instead, it is forcing ship captains to obey: use Iran's routes or risk being attacked.

Ship companies and insurers now face higher costs. Insurance that covers war risk—damage from attacks—has become more expensive since Iran hit the MSC-Francesca in April. Iran's new announcement will raise prices further. Shipping companies have to decide: does this threat last, or will it fade like past tensions have?

Who Gets Hit Hardest

Ship owners and cargo companies are squeezed three ways. Insurance costs more. Ship captains do not want to go through the Strait without protection. And if ships go around Africa instead, the voyage takes 10–14 extra days and costs much more. Liquid natural gas from Qatar and crude oil from Iraq both travel through the Strait to Europe and Asia. Disruption there affects energy prices worldwide.

This is not entirely new. Wars over tanker shipping happened in the 1980s. Ships were seized in 2019. Red Sea attacks hit shipping in 2023 and 2024. But this time is different in one way: Iran is not just attacking ships randomly. It is making a formal system. Ships must use Iran's routes or face trouble. That is stronger control than random attacks, and it is what shipping companies and energy traders need to watch most carefully.