A United Nations tribunal has ordered Russia to immediately release three Ukrainian naval ships and two dozen sailors, who were captured in a November confrontation off the Crimean Peninsula.

The Germany-based International Tribunal for the Law of the Sea issued the order Saturday after a hearing earlier this month.

The seizures occurred during a November 25 confrontation in the Kerch Strait, which separates Crimea from mainland Russia. It was the first open military clash between Russia and Ukraine since Moscow’s 2014 annexation of the Crimean Peninsula, which is generally regarded as an illegal action.

Ukraine maintains Russia stopped its ships in the Black Sea as they were returning to the Ukrainian port city of Odessa. Ukraine argues its ships were immune to such seizures under the Law of the Sea.

Russia contends the vessels were trying to enter the Azov Sea through the Kerch Strait in defiance of Russian orders to stop because it had temporarily closed the waterway.

Russia has charged the crew with violating its border and argues the tribunal does not have jurisdiction over the issue because of an exemption for military activity. Russia did not attend the hearing or Saturday’s tribunal session.

The Hamburg tribunal’s rulings are legally binding, but it lacks the power to enforce them. It gave both sides until June 25 to report on compliance with its order.