FYI, Crimea has been a part of Russia for over 200 years, except for the post Soviet Union period, which in and of itself was the result of a symbolic transfer of Crimea to the Ukranian SSR in 1954, marking the 300th year of the Ukraine under Russian rule. A move, which was supposed to have no strategic consequence, until the Soviet Union broke up and twenty years later NATO attempted to bring the Ukraine into their fold.

Of course Russia could not allow their warm water port to fall under NATO jurisdiction