No International Waters

On April 7, 2026, Iran agreed to a two-week ceasefire with the United States and announced what it called “controlled passage” through the Strait of Hormuz. The terms were simple: any commercial vessel transiting the strait would coordinate with Iran’s armed forces, follow designated routes, and pay a transit fee. Western commentators called it extortion. Tehran called it governance.

Most people assume Iran is simply threatening to block an international waterway — that it’s holding the world’s oil supply hostage by menacing a corridor that belongs to everyone and no one. That framing is everywhere: in cable news chyrons, in Pentagon briefings, in op-eds that invoke “freedom of navigation” like an incantation.

The geography tells a different story. There are no international waters in the Strait of Hormuz.

The Strait by Numbers

The Strait of Hormuz stretches roughly 104 miles, connecting the Persian Gulf to the Gulf of Oman and, beyond it, the Arabian Sea and the open Indian Ocean. Iran sits on the northern shore. Oman’s Musandam Peninsula — a jagged finger of rock separated from the rest of Oman by the UAE — forms the southern shore.

At its narrowest point, the strait is just 21 nautical miles wide.

Through this narrow passage flows roughly 20 million barrels of crude oil every day — about one-fifth of global consumption. Add in refined petroleum products, liquefied natural gas, and non-energy cargo, and the strait handles more than $700 billion in goods annually. There is no alternative route with comparable capacity. The few pipelines that bypass Hormuz carry a fraction of the volume.

Every map of the strait tells the same story: two coastlines closing in on each other like the jaws of a vise, with the world’s most valuable shipping lane squeezed between them.

No High-Seas Corridor

Under the United Nations Convention on the Law of the Sea, a coastal state may claim territorial waters extending 12 nautical miles from its baseline. Both Iran and Oman do exactly that.

Here is the arithmetic that changes everything: 12 nautical miles from Iran plus 12 nautical miles from Oman equals 24 nautical miles. The strait at its narrowest is 21 nautical miles. The territorial claims don’t just meet in the middle — they overlap.

The entire strait, at its chokepoint, falls within sovereign territorial waters. There is no sliver of high seas. No international corridor. No neutral space. Every drop of water in that passage belongs, legally, to either Iran or Oman.

This makes the Strait of Hormuz almost unique among the world’s major shipping lanes. The Strait of Malacca, which connects the Indian and Pacific Oceans, is 1.5 nautical miles wide at its narrowest but opens to 40 miles across — with generous high-seas margins. The English Channel has international waters running down its center. The Bab el-Mandeb strait at the southern end of the Red Sea is 16 miles wide at minimum, but the territorial claims of Yemen and Djibouti leave a navigable international corridor. Hormuz has none.

Iran’s Unsinkable Aircraft Carriers

Geography gave Iran more than a coastline. It gave Iran islands — seven of the eight major islands in the strait area, scattered across the approaches like fortified stepping stones. Each one extends Iran’s territorial reach, each one hosts military infrastructure, and together they form a layered defense network that makes the strait not just narrow but surveilled from every angle.

Qeshm Island

At 1,491 square kilometers, Qeshm is the largest island in the Persian Gulf. It sits just off Iran’s southern coast, stretching 135 kilometers along the northern approaches to the strait. Its sheer size dominates the geography. Iran operates naval bases, IRGC garrisons, and radar installations across the island. Qeshm is less a military outpost than a military district.

Hormuz Island

The strait’s namesake. At 42 square kilometers, Hormuz Island sits at the mouth of the passage, the geographic landmark that defines the entire chokepoint. It has been fortified and garrisoned for centuries — by the Portuguese in the 1500s, by Safavid Persia after that, and by the IRGC today.

Larak Island

Larak sits deeper in the strait, positioned to monitor vessel traffic from a vantage point that covers both inbound and outbound lanes. Iran operates Kashf-99 radar installations on Larak and has used the island as a vessel inspection point — ships intercepted by the IRGC Navy for regulatory violations have been brought to Larak for inspection.

Abu Musa

Disputed with the UAE and Iran reasserted control in 1971 as Britain withdrew from the Persian Gulf. Abu Musa is the most heavily fortified of the disputed islands. Iran has installed Fateh ballistic missiles with a 120-kilometer range, Qader anti-ship cruise missiles capable of reaching targets more than 300 kilometers away, 15 Khordad surface-to-air missile systems, and Shahed-136 drone launch facilities. The garrison exceeds 1,000 IRGC personnel.

Greater Tunb and Lesser Tunb

Also brought under Iranian control in 1971, also disputed with the UAE, and also fortified. Greater Tunb and Lesser Tunb extend Iran’s radar and missile coverage southward into the strait, creating overlapping fields of fire with Abu Musa and Larak. The UAE has never recognized Iran’s sovereignty over any of the three disputed islands, and the dispute surfaces at every GCC summit. It has never been resolved.

The military picture is layered: Fateh ballistic missiles for striking airbases and ports, Qader cruise missiles for hitting ships at extreme range, Kashf-99 radars providing persistent surveillance, 15 Khordad SAM batteries to deny airspace, and Shahed-136 one-way attack drones for swarming targets that survive the first salvo. Every island is a sensor node, a missile battery, and a garrison — unsinkable aircraft carriers arrayed across the world’s most important shipping lane.

The Traffic Separation Scheme

Since 1979, the International Maritime Organization has designated formal shipping lanes through the strait under what is called a Traffic Separation Scheme. The system works like a divided highway.

Ships entering the Persian Gulf use an inbound lane on the northern side, roughly 2 nautical miles wide. Ships exiting the Gulf use an outbound lane on the southern side, also about 2 nautical miles wide. Between them sits a 2-nautical-mile buffer zone. The total navigable corridor is approximately 6 nautical miles across.

Now comes the geographic detail that upends the conventional narrative. At the narrowest chokepoint, the Musandam Peninsula juts northward into the strait. This projection pushes Oman’s territorial waters deep into the passage. The result: at the critical bottleneck, both the inbound and outbound shipping lanes — along with the buffer zone between them — lie within Omani territorial waters.

Iran controls the approaches. Iran’s islands dominate the surrounding waters. Iran’s missiles and radars cover the entire passage. But the six-mile-wide corridor where tankers actually transit? That belongs to Oman.

This is why Oman’s position in this crisis matters far more than most analysts acknowledge. Oman is not a bystander. It is the quiet sovereign of the bottleneck itself — and it has spent decades cultivating relationships with both Washington and Tehran.

The Legal Gray Zone

The UN Convention on the Law of the Sea, specifically Part III, governs straits used for international navigation. Article 38 establishes the right of “transit passage” — meaning ships and aircraft may pass through such straits without prior authorization, without stopping, and without being obstructed. Article 44 is blunt: transit passage “shall not be suspended.” No exceptions.

If the law were that simple, there would be no story here. It is not that simple.

Iran signed UNCLOS in 1982 but has never ratified it. Upon signing, Iran filed a declaration stating that only states that are party to the convention may benefit from its rights — including transit passage. This declaration has been a quiet legal time bomb for four decades.

In 1993, Iran passed a domestic maritime law requiring foreign warships to obtain prior authorization before transiting the strait. Submarines must surface and show their flag. Commercial vessels must use designated sea lanes and communicate with Iranian authorities. These requirements directly contradict UNCLOS, which permits unimpeded transit passage for all vessels.

Most international law scholars argue that transit passage through straits used for international navigation has become customary international law — binding on all states regardless of treaty ratification. Under this view, Iran cannot legally restrict passage even though it never ratified the convention.

The implications of that scholarly consensus are significant. If transit passage is customary international law, then Iran’s restrictions are not a gray-area interpretation of an ambiguous treaty. They are a violation of a binding norm — one that the International Court of Justice has recognized in the Corfu Channel case of 1949, which established that warships have a right of innocent passage through international straits even without the strait state’s consent. The US Navy’s position, shared by the navies of Britain, France, and most NATO allies, is that transit passage through Hormuz is not a privilege Iran can revoke. It is a right the world has exercised for decades, codified in practice even where the treaty remains unsigned.

But “most scholars agree” is not the same as “settled.” Iran disputes the customary law argument. And here is the detail that American commentators rarely mention: the United States has also never ratified UNCLOS. Washington signed the 1994 Implementation Agreement and treats UNCLOS as reflecting customary international law, but the Senate has never given its advice and consent. The world’s two loudest voices in this dispute both sit outside the treaty they invoke.

The legal ambiguity is not academic. It is the space in which Iran is now operating. When your legal position has even a five-percent chance of holding up, and you have the missiles and geography to enforce it, ambiguity becomes leverage.

What This Means Now

Zoom back to April 7, 2026. Iran’s announcement of “controlled passage coordinated with armed forces” is not the reckless gambit that Western hawks describe. It is a deliberate exploitation of the geography just described.

Iran does not need to close the strait. It does not need to sink a tanker or mine a shipping lane. It just needs to make passage conditional. Show your manifest. Coordinate your route. Pay the fee. Follow the rules — our rules.

The selective access policy Iran has implemented since the war began makes this even clearer. Ships flagged to Western nations or carrying cargo to Western ports face delays, inspections, or outright denial of passage. Ships carrying oil to India, China, and Pakistan pass through with a wave from the IRGC. The strait has become a tollbooth — not closed, but filtered.

Iran has now introduced formal legislation in the Majlis to codify transit fees for the strait. The bill draws explicitly on historical precedent — centuries of strait tolls collected by sovereign states, from the Ottoman Empire’s Bosphorus dues to Denmark’s Sound Dues, which lasted 428 years.

This arrangement would be impossible at the Strait of Malacca, where international waters provide ships with an alternative routing outside any state’s territorial jurisdiction. It would be impossible at the Panama or Suez Canals, which are governed by specific international treaties. But at Hormuz, the geography creates an opening that international law has never fully closed.

Understanding this geography is not about sympathizing with Iran’s position. It is about understanding what is actually happening. The conversation in Washington about “freedom of navigation” assumes a legal and geographic framework that does not exist at this particular strait. Until that assumption is corrected, the policy responses will keep missing the mark.

In the next article in this series, we examine how Iran has already closed the strait without firing a shot — not with missiles or mines, but through the insurance market. When Lloyd’s of London raises the war-risk premium on a tanker transit, the cargo never loads in the first place.