Who Controls the Strait of Hormuz? Is It International Waters?

No: there are no international waters, in the sense of high seas, in the narrows of the Strait of Hormuz. Iran extended its territorial sea to 12 nautical miles in 1959 and Oman did the same in 1972, and Oman restated the 12-mile limit when it ratified the UN Convention on the Law of the Sea in 1989. Because the strait is less than 24 nautical miles wide at its narrowest, the two claims meet in the middle, so every ship crossing that stretch is in either Iranian or Omani waters.

The strait is still international in a legal sense. Because it links the open waters of the Persian Gulf and the Gulf of Oman and carries constant traffic, it is a “strait used for international navigation” under Part III of the convention. Article 34 adds that this does not change the status of the water: Iran and Oman keep their sovereignty over it, and the world’s ships keep a right to cross it.

Both do, each on its own side: Iran holds the northern half and Oman, through its Musandam Peninsula exclave, holds the southern half. The international shipping lanes, two channels each about two nautical miles wide under a traffic separation scheme adopted in 1968, run through Oman’s territorial waters at the narrowest point, as we explain in How Wide Is the Strait of Hormuz?.

Iran, however, holds the islands around the water. Hormuz, Qeshm, Larak and Hengam sit off its coast beside the lanes, and since 1971 it has also held Abu Musa and the Greater and Lesser Tunbs to the west, which the United Arab Emirates still claims. From bases there the Revolutionary Guards watch every passing ship, which is why Qeshm Island matters so much.

Transit passage is the stronger right: all ships and aircraft may cross a strait without stopping, and the coastal states may not impede it. Article 38 of the convention defines it as freedom of navigation and overflight “solely for the purpose of continuous and expeditious transit,” and Article 44 says “there shall be no suspension of transit passage.”

Innocent passage is weaker. It covers ships but not aircraft, requires submarines to surface, and lets the coastal state stop a passage it judges not innocent, though in an international strait it still may not be suspended.

Which regime applies is the heart of the dispute. Iran signed the convention on December 10, 1982, with a declaration that only states that are parties to it may benefit from its “contractual rights,” naming transit passage, and that coastal states may require prior authorization for warships. Iran has never ratified the treaty. Its Marine Areas Act of May 2, 1993 refers only to innocent passage and requires prior permission for warships, submarines and nuclear-powered ships. Oman signed on July 1, 1983 and ratified on August 17, 1989, with its own declaration that warships’ innocent passage through its waters is subject to prior permission. The United States is not among the convention’s 172 parties either, but it holds that transit passage is customary law binding on every state, as President Ronald Reagan’s ocean policy statement of March 10, 1983 set out.

In peacetime, no: under either regime a coastal state may not suspend passage through an international strait. Iran argues instead that it may refuse passage it considers not innocent, and that wartime rules apply.

Those rules give a belligerent more room, not a free hand. The 1994 San Remo Manual on armed conflict at sea, which most navies follow, lets a party to a war act against enemy ships in a strait but requires it to leave neutral shipping a way through; mining a strait shut with no safe route would be unlawful.

Iran says it leaves that way open. In a statement to the International Maritime Organization in March 2026, it said “non-hostile” vessels could cross if they coordinated with Iranian authorities, while ships of the United States, Israel and other participants in what it called the aggression did not qualify for innocent passage. Foreign Minister Abbas Araghchi said in late March that barring the vessels of aggressors and their allies was Iran’s legal right as a coastal state. The United States and the Gulf exporters reject that reading: a strait where one belligerent picks the ships, the routes and the price is, for them, a closed strait.

Not under the law of the sea. Article 26 of the convention says no charges may be levied on foreign ships by reason only of their passage, and that fees may be charged only for specific services rendered to a ship, without discrimination.

Iran has moved toward charging anyway. In late March 2026 lawmakers advanced a bill to charge ships crossing the strait and to bar vessels of the United States, Israel and countries that joined sanctions on Iran; the parliament’s security committee approved a further article in August, but no final vote or Guardian Council approval has been confirmed. On May 5, Iran’s state broadcaster announced a Persian Gulf Strait Authority as a “single window” through which shipowners arrange transits with the Revolutionary Guards’ navy. On May 1 the US Treasury warned that paying Iran for passage in any form could bring US sanctions, and it widened the warning on August 24. Saudi Arabia insists that any reopening must be free of fees and restrictions.

As of November 9, 2026, Iran controls who crosses the Strait of Hormuz, and the United States controls who reaches Iran’s ports. Iran enforces its routes with mines, anti-ship missiles, drones and the Guards’ fast boats; on April 8 it published a redrawn traffic scheme that sends ships between Qeshm and Larak, inside its own waters, and marked the old Omani lanes a danger zone. How many mines it could lay is set out in How Many Naval Mines Does Iran Have?

Washington answers with force. Its navy enforces a blockade of Iranian ports, a White House statement of August 28 asserted American control of the strait and said nearly 1,500 commercial ships had crossed under US protection, and in early November the head of US Central Command, Adm. Brad Cooper, said the main routes were clear of Iranian mines, which Iran disputes.

Oman, which owns the lanes, has chosen diplomacy. It opened two temporary routes on June 24, and on August 25 it agreed with Iran on a temporary navigation corridor and joint mine clearance, pledging to respect international law and the coastal states’ sovereign rights. The traffic count shows the result: about 78 crossings a day from July 2025 until the war began, against about three a day in October 2026.

The Strait of Hormuz is about 21 nautical miles wide at its narrowest point, between Iran’s Larak Island and Oman’s Quoin islands. Iran claims a 12-mile territorial sea under a 1959 law; Oman claims 12 miles under a 1972 decree. Iran signed the UN Convention on the Law of the Sea on December 10, 1982 and has never ratified it. Oman ratified the convention on August 17, 1989. The United States is not a party but has treated transit passage as customary law since March 10, 1983. Article 44 of the convention says there shall be no suspension of transit passage, and Article 26 bars charges for passage alone. Before the 2026 war, about 78 ships a day crossed the strait.