President Trump last week said that after defeating Iran he would declare the Strait of Hormuz US territory and has previously asserted the US “owns” the waterway, despite parts lying within Iranian and Omani territorial seas. Maritime law experts say such a claim faces major legal obstacles. A City, University of London maritime-law professor said under US law a presidential proclamation or order alone would be insufficient to claim territory and would have to meet constitutional requirements.

President Trump last week said that after defeating Iran he would declare the Strait of Hormuz US territory and has previously asserted the US “owns” the waterway, despite parts lying within Iranian and Omani territorial seas. Maritime law experts say such a claim faces major legal obstacles. A City, University of London maritime-law professor said under US law a presidential proclamation or order alone would be insufficient to claim territory and would have to meet constitutional requirements. Under international law, annexation would violate the UN Charter; territory, including maritime areas, can only be acquired by treaty or cession. Occupation may give de facto control but does not confer legal title, a Swansea shipping-law professor said, and any transfer would require Iran’s consent, which is highly unlikely. The professor added a hypothetical US–Iran–Oman deal to open the strait and levy transit fees would also conflict with international law and UNCLOS. Experts emphasized Iran and Oman do not have absolute property rights over the strait; freedom of navigation is the governing legal principle and military control does not equal legal ownership.