Oral arguments begin in the international Permanent Court of Arbitration in The Hague on October 11 in the latest round of a long-running dispute over Russia's seizure of three Ukrainian Navy vessels in the Kerch Strait in 2018.
The case is part of long-standing tensions since Russia forcibly annexed the Crimean Peninsula in 2014 and claimed exclusive navigation and other rights to nearby waters of the Black Sea.
Russian representatives were scheduled to present their objections first, with Ukraine to follow in at least four days of argument.
Ukraine filed a claim with the international arbitrators in 2019 after the Russian coast-guard seized two Ukrainian gunboats and a tugboat as they maneuvered near the Kerch Strait between Crimea and Russia.
The seizure was a serious escalation in tensions between the neighbors against the backdrop of an ongoing war between Ukraine and Moscow-backed separatists that is now in its eighth year.
The case hinges on maritime zones and sovereignty over the waters in question, including the Sea of Azov and the Kerch Strait.
Russian authorities charged the ships' crews with illegally crossing the Russian border as they reportedly sailed between the Ukrainian ports of Odesa and Mariupol.
Russia returned the 24 Ukrainian sailors 10 months later and the boats nearly a year after the incident.
The United Nations continues to recognize Crimea as Ukrainian territory.
Ukrainian officials have launched other international cases against Russian actions in Crimea, including before human rights courts.
The Ukrainian Foreign Ministry has said it doesn't expect a verdict in the arbitration case over the naval seizures until at least 2022.
