Russia's fear of the Black Sea? Putin's fleet in distress. Russia could attack relatively safely from the eastern Black Sea, according to British intelligence.
British intelligence also reported deficiencies in Russian strategy “against Ukraine’s unconventional approach to maritime warfare” Ukraine does not have a particularly large navy, but has recently successfully used naval drones. There are the Mediterranean Sea no carriers of cruise missiles, no cruise missiles of Kalibr, and no enemy ships in the Sea of Azov.