You're completely ignorant. The Russians have operated a naval base in Crimea since the last 1700s including during the period of time you reference.
Crimea was not Russian territory from 1991 to 2014. It still isn’t internationally recognized as Russian territory. They operated the naval base in Sebastopol together with the Ukrainians by treaty. Since they violated both the Budapest memoranda and the naval treaty, Russia no longer has any right to use Sebastopol. Whether anyone will be willing or able to force them out is another question.