You Can't Annex a Strait, and Trump's Hormuz Claim Proves Why He Needs One

For four decades the United States sent warships through the Strait of Hormuz to make a single legal point: nobody owns it. Since President Reagan endorsed the navigation rules of the UN Convention on the Law of the Sea in 1982, American policy has held that the 21-mile-wide channel between Iran and Oman, the passage for roughly a fifth of the world's oil, is an international strait through which every nation's ships enjoy unimpedable transit⁵. The Navy ran convoys through it in 1987 to defend that principle against Iranian mines. So there was a certain historical vertigo in watching President Trump tell a Long Island crowd on Friday that "pretty soon I'll be declaring the Hormuz Strait a territory of the United States,"¹ two days after posting that America has total control of the waterway and might keep it.

The question worth asking is not whether the annexation is legal. It is not, and I have found no serious lawyer who argues otherwise. Sovereignty over Hormuz belongs to the two coastal states whose territorial waters make up the strait, Iran on the north shore and Oman on the south², and the entire body of law the US helped write exists to prevent any state, littoral or otherwise, from turning it into property. The more useful question is what the claim reveals about the war's actual balance of power on the water. Work through that, and the territorial talk starts to look less like a maximalist negotiating position and more like a confession.

Start with the legal self-sabotage, because it is genuinely strange. Iran's longstanding position is that, since neither it nor the US ratified UNCLOS, foreign ships enjoy only "innocent passage," a weaker right that a coastal state can suspend; Washington has always countered⁶ that transit passage hardened into customary law binding on everyone. Every element of Trump's Hormuz policy this summer, from the abandoned 20 percent toll proposal that legal scholars called a clear violation⁷ of the convention, to Friday's territory vow, adopts Tehran's legal theory: the strait is a thing a state can own, close, and charge for. Secretary of State Marco Rubio stated the American position himself when Iran floated tolls: "No country is allowed to charge tolls or fees on an international waterway."⁸ The EU and the Gulf Cooperation Council, the coalition that shares Washington's interest in breaking Iran's grip, issued a joint statement in July that "reject as unlawful any assertion of sovereignty or control over the Strait of Hormuz by any State"⁹ — language aimed at Tehran that now catches Washington in the same net.

There is a real argument for the policy underneath the rhetoric, and it deserves to be stated fairly. The blockade of Iranian ports, reimposed in July after the ceasefire memorandum collapsed, is a recognized instrument of war in a way annexation never will be, and the case for it runs like this: Iran closed the strait first, only unambiguous force ever moves Tehran, and the 1987-88 Tanker War showed that sustained American naval pressure can change Iranian behavior¹⁰. On pure denial, the record backs the White House. When a Panama-flagged container ship ran for an Iranian port last week, a Navy helicopter disabled its steering gear with Hellfire missiles¹¹, the twelfth vessel the US has fired on. When Trump says "no ships get through unless we want them to,"³ he is describing something true.

But denial was never the goal, and the distinction is where the coercion case falls apart. Control of a trade artery means the ability to make commerce flow through it safely, and by that measure nobody controls Hormuz right now. Just nine commercial vessels¹² transited on Thursday, against a pre-war norm of 130 to 178 a day, a collapse of roughly 95 percent¹³. War-risk insurance for a Hormuz crossing has climbed to 3 to 10 percent of a ship's hull value¹⁴, up from 0.25 percent before the war, meaning a $100 million tanker pays up to $10 million for one voyage. The International Energy Agency now expects global oil demand to shrink by 1.6 million barrels a day¹⁵ this year, with 8.3 million barrels of Gulf output still shut in. Six months of blockade have not produced the promised concessions either. Iran's security establishment has named the blockade itself as the obstacle, conditioning any reopening¹⁶ on American withdrawal, and Foreign Minister Abbas Araghchi says no negotiations with Washington are even underway. Meanwhile Iran's proxies are escalating rather than folding: Houthi missiles killed six people¹⁷ aboard a cargo ship in the Bab el-Mandeb last week, the deadliest shipping attack of the war, spreading the chokepoint crisis to a second strait. The 1987 precedent involved convoying tankers to keep oil moving while striking Iranian assets that interfered. The 2026 version has inverted it: American power is now one of two forces keeping the world's most important oil corridor shut.

All of this is happening, moreover, in a constitutional void the annexation talk would deepen. Congress has never authorized this war. Both chambers passed a war powers resolution in June directing Trump to withdraw from hostilities¹⁸, the House passed a second one in July¹⁹, and the administration has treated both as suggestions. A president claiming territory by speech, while waging a war Congress has twice voted to end, is not a strong legal position from which to ask allies to underwrite a maritime order.

The sharpest evidence that the territorial claim is compensating for lost leverage is the deal actually taking shape. Iran and Oman, the two states that own the strait's waters, have agreed on coordinates for new shipping lanes²⁰ after weeks of bilateral talks, with a joint coordination center to manage traffic. Washington is not a party. And the routes tell the story: inbound traffic would run through a northern lane in Iranian territorial waters, displacing the decades-old system in which commerce moved through Oman's side of the strait. If that arrangement sticks, the war's maritime endgame will have shifted the strait's traffic architecture toward Tehran, under an agreement negotiated around the United States, while an American president declared the waterway his. Iran's deputy foreign minister answered Friday's speech by saying the strait "cannot be seized by tweet, nor by aircraft carrier."⁴ The taunt is cheap, but the map coordinates behind it are not. Watch where the reopened lanes run, because whoever's territorial waters carry the tankers will have won the strait, whatever anyone declares from a stage on Long Island.