Was the US Seizure of the Iranian Ship Legal? The Maritime Framework
Context:
On April 19, the United States intercepted and seized an Iran-flagged cargo ship, the Touska, in the Gulf of Oman.
Following six hours of ignored radio and visual warnings from the US Central Command (CENTCOM), the USS Spruance struck the ship's engine room, allowing US Marines to board and take custody.
The Legal Dispute:
The United States defended the military operation as a lawful enforcement mechanism to protect the integrity of its naval blockade on Iranian ports, which it declared on April 13.
The Maritime Legal Framework:
The legality of the US action hinges entirely on how the international community interprets the status of the broader conflict, specifically whether the April 8 ceasefire successfully terminated the state of armed conflict.
The Peacetime Scenario:
If the April 8 ceasefire is interpreted as establishing a state of peacetime, the US Commander's Handbook on the Law of Naval Operations holds no legal weight.
In a peacetime scenario, the US naval blockade and the seizure of the Touska are considered illegal acts of piracy under the United Nations Convention on the Law of the Sea (UNCLOS).
The Wartime Scenario (Geneva Convention):
If it is deemed that the US and Iran remain in an international armed conflict, the US actions may be legally valid.
Under wartime rules, a neutral vessel that actively ignores warnings to stop loses its civilian immunity and is reclassified as an "enemy merchant vessel".
While such a vessel is not legally bound to stop and may resist, it assumes all risks of resulting damage.
By warning the Touska's crew to evacuate the engine room and choosing to disable propulsion rather than sink the ship entirely, the US Navy appears to have adhered to the wartime rules of "proportionality" and "precaution" set down by the Geneva Convention to minimize civilian casualties.