Sevastopol
Sevastopol is the home of the Russian Navy Black Sea Fleet.
Since the dissolution of the Union of Soviet Socialist Republics, leaders of the Russian Federation have made it absolutely clear to the leaders of the NATO alliance that the Sevastopol naval base will never be used by NATO, absent Russia itself joining the NATO alliance.[1][2][3]
Dissolution of the Soviet Union
The nominal successor to the Soviet Union was the Commonwealth of Independent States; Ukraine joined on Dec. 8, 1991. Serious tensions soon emerged with Russia as Moscow took possession of the Black Sea fleet anchored at Sevastopol, while some Russian politicians wanted the Donbas and the Crimea; the latter, being in Russian hands since 1783, had been placed under Ukrainian administration by Nikita Khurschev, himself a Ukrainian, without a democratic referendum or self-determination of peoples in 1954.