Russia has built a missile stronghold in Russian-occupied Crimea to push an anti-air and anti-ship umbrella over the Black Sea:
The objective is to use the umbrella it has created as the basis for an even more expansive strategy (resembling that used by the Egyptian Army in the Yom Kippur War of 1973 to cross the Suez Canal and attack Israeli forces) from which it can project power further out and deny those areas to NATO or at least threaten NATOI with heavy costs.
For example, in response to talk of NATO exercises, Andrei Kelin, a spokesman for the Ministry of Foreign Affairs labeled such exercises destabilizing and further added that, “This is not NATO’s maritime space and it has no relation to the alliance.” ...
Thus Moscow’s reinforcement of the Black Sea Fleet and surrounding forces enabled it to build a platform for denying NATO access to that sea, Ukraine, Russia, and the Caucasus and to serve as a platform for power projection into the Mediterranean and Middle East.
And since the intervention in Syria in 2015 Moscow has started to fortify the missile, air defense, and submarine component of its Mediterranean Eskadra (Squadron) to impart to it a capability for denying the Eastern Mediterranean area and access to it by NATO fleets in the Mediterranean.
Please note that some time ago I said that Russia' intervention in Syria was made possible by taking Crimea; and that taking Crimea really made sense as a power projection platform to push Russian influence into the eastern Mediterranean Sea.
UPDATE: Of course a limiting factor in Russian power projection is Turkey, which controls the straits between the Black Sea and the Mediterranean Sea.
As much as Turkey is alienating NATO, I don't think Erdogan wants to trade (not for long, anyway) a benign alliance posing no threat to Turkey for a Russian ally who has paranoia to match the long string of Russian-Turkish wars.
