Who Actually Controls the Strait of Hormuz? The Legal Reality Is Stranger Than You Think

Everyone talks about Iran blocking the Strait of Hormuz. But the legal geography of the strait is far more complex. Here is who actually has jurisdiction over what.

The Strait of Hormuz is, in the popular imagination, an Iranian waterway that Iran can open or close at will. This is not quite accurate, and the inaccuracy has significant implications for understanding both the legal basis of the current crisis and the options available to resolve it.

The strait's geography involves two countries: Iran on the northern shore and the Sultanate of Oman on the southern shore, with the island of Musandam — an exclave of Oman separated from the mainland — forming the southern boundary of the narrowest point. The navigational channels that tankers use pass through the territorial waters of both countries, not through international waters or through Iranian territorial waters alone.

Under the United Nations Convention on the Law of the Sea (UNCLOS), ships have the right of 'transit passage' through international straits connecting two areas of international waters — a right that cannot be suspended even by the coastal states. The Strait of Hormuz qualifies as such a strait under UNCLOS's definition. Iran, however, has not ratified UNCLOS, and maintains a position under its domestic maritime law that is partially at odds with UNCLOS's transit passage provisions.

In practice, Iran's ability to restrict or threaten transit through Hormuz derives not from legal authority but from military capacity: the ability to lay mines, deploy anti-ship missiles, interdict vessels with naval forces, or use drones to make transit hazardous regardless of what international law says. The legal position of unrestricted transit passage coexists, uneasily, with the physical reality that a military power can impose costs on transit regardless of the legal framework.

Oman's role is often overlooked. As the other littoral state, Oman has a stake in the functionality of the strait and has historically used its position as a neutral, diplomatically active Gulf state to facilitate communications between Iran and Western parties in exactly the kind of crisis now underway. The Omani government has been active in diplomatic channels throughout the current crisis, providing one of the few functioning communication bridges between Tehran and Washington.