“The Russian Federation must proceeed immediately to release the Ukrainian soldiers and allow them to return to the Ukraine,” said Judge Jin-Hyuan Paik at the International Tribunal for the Law of the Sea, which is located in the German port city of Hamburg.
The tribunal judges additionally ruled Russia should “immediately” return three Ukrainian navy vessels it seized in the Kerch peninsula off Crimea, which Moscow annexed in 2014.
Ukraine took the matter to the tribunal last month although Russia does not recognise its jurisdiction to rule in the affair and has not sent representatives to the hearing.
“The tribunal ruling is a clear signal to Russia that it cannot violate international law with impunity,” Ukraine's vice minister for foreign affairs Olena Zerkal said on her Facebook page after the judgement.
Zerkal added Russia should “conform swiftly and wholly” with the ruling.
Russia has accused the sailors of violating its maritime borders. The Ukrainian sailors face up to six years in prison if found guilty in what Kremlin critics have warned could be a show trial.