Closing the Strait of Hormuz isn’t enough for Iran–it wants to own it. Iran has rejected President Trump’s peace plan and demanded U.S recognition of its sovereignty over the Strait. The United States should refuse loudly and on principle. Granting Iran sovereignty over the Strait would blow up the legal architecture that keeps every maritime chokepoint on earth open, and hand China, Russia, and every other would-be tollbooth state a roadmap to do the same.
Iran Is Illegally Controlling the Strait of Hormuz
The Strait of Hormuz runs between Iran and Oman, connecting the Persian Gulf to the Gulf of Oman. Approximately 27% of the world’s crude oil and petroleum products, and 20% of global liquefied natural gas, typically pass through the 22-mile wide Strait. Iranian forces declared the Strait closed on March 4, sending global commerce into crisis. It has reportedly been mining the Strait, extending the time before it can be cleared for commercial use. Further closure of the Strait may trigger global famine due to stalled transit of agricultural products and fertilizer.
Meanwhile, Iran has shown that it can selectively control the Strait. Iranian tankers bound for China have been transiting the Strait at higher numbers than before the war. Yesterday President Trump announced that Iran allowed 10 oil tankers with Pakistani flags through the Strait as a “present” to the United States. Pakistan has emerged as a key interlocutor between the United States and Iran.
Iran has no legal basis for its actions. Under the UN Convention of the Law of the Sea (UNCLOS), a strait is a narrow, natural waterway conducting two parts of the high seas or an exclusive economic zone (EEZ). Foreign ships and aircraft have the right of transit passage through straits. This means foreign vessels have freedom of navigation and overflight through the Strait for continuous and expeditious transit. Coastal states cannot impede transit passage. Transit passage is widely considered part of customary international law that is binding on all nations, unless those nations persistently object to prevent the formation of custom. Iran signed but did not ratify UNCLOS, and has objected to the concept of transit passage, but not consistently. Iran’s vessels take advantage of transit passage elsewhere and it makes other claims consistent with transit passage. Moreover, Iran is violating other states’ rights. There is no comparable way for oil and other lifeline materials to enter coastal states or exit the Gulf. Iran is also violating Oman’s maritime rights.
Iran is running a de facto and illegal blockade of the Strait. For a belligerent to legally blockade a waterway, a blockade must be declared by proper authority, applied impartially to vessels of all states, and must not bar access to or departure from neutral ports and coasts. Also, a blockade is legal only when a “route of similar convenience” available to neutral shipping. Iran’s closure of the Strait is blatantly illegal, and the international community may legally use force to open it.
Why Iran Wants Sovereignty Over The Strait of Hormuz, Not Just Control
Why does Iran want legal recognition of its sovereignty over the Strait when it already has power to control it? Because illegality is a double-edged sword. Iran’s ability to inflict damage in the short term and control the Strait in the long term both depend on the force of law. Closing the Strait triggers a market crisis and international outrage that give Iran leverage in the short term. But it also makes Iran a global outlaw and hands the international community a legal justification to use force. The Trump administration is trying to build that coalition right now. Iran does not want international warships at its doorstep for the long term.
Sovereignty would transform Iran’s position overnight. Closing the Strait would no longer be an act of war. It would be domestic regulation, beyond the reach of international law and nearly immune to legal international military intervention. Iran could charge whatever tolls it wanted, demand permission from foreign vessels to transit, deny passage to U.S. or Israeli ships, and open and close the chokepoint at will to shock global markets. Iran would have effective control over 27% of the world’s petroleum products.
Recognizing Iran’s sovereignty over the Strait would create a dangerous precedent. It would open the door for other rogue actors to seize and claim control over straits worldwide. China is already practicing a blockade of the Taiwan Strait, home to half of global container shipping. China could also block the Strait of Malacca, the world’s busiest shipping lane. Russia is already extracting tolls in the Northern Sea Route, a thawing Arctic waterway that it illegally claims. The Houthis have shown that even a non-state actor can functionally close Bab El-Mandeb, choking Red Sea trade. An Iranian legal victory in the Strait of Hormuz would signal to these actors that seizing a chokepoint and daring the world to respond can be converted into permanent, legally-recognized control.
Iran is seeking recognition under international law as a prize for defying it. Trump’s answer will almost surely be no, but the world needs more. The United States has an opportunity to declare unambiguously that no state may claim sovereignty over an international strait, that freedom of the seas is not negotiable, and that it will defend the international legal architecture protecting global trade. Trump’s National Security Strategy emphasizes the importance of keeping critical waterways “open, free of ‘tolls,’ and not subject to arbitrary closure by one country.” This is a chance for the President to assert what he stands for.