A United Nations tribunal was set to issue a ruling in the dispute over Russia's detention of two dozen Ukrainian sailors, and the seizure of three Ukrainian ships near Crimea last year.
The May 25 ruling by the International Tribunal for the Law of the Sea is unlikely to definitively end the question of allowing Ukrainian ships full access to the Sea of Azov, which Russia has been restricting since a bridge across the Kerch Strait was completed.
But Ukraine is hoping a victory will provide legal weight in its fight against Russia, which has boycotted the proceedings, saying the court has no jurisdiction.
Russia seized the ships in November near the Kerch Strait bridge, which connects the Russian mainland to the Black Sea peninsula of Crimea. Moscow annexed the Ukrainian peninsula in 2014.
Ukraine has denied Russia's charge that the Ukrainian ships had entered Russian territorial waters illegally.
The European Union, NATO, and other international bodies have called on Moscow to release the ships and the detained sailors.
