The command of the Black Sea Fleet of the Russian Federation almost certainly redeployed Kilo-class submarines from the home port of Sevastopol to Novorossiysk in the Krasnodar Territory in southern Russia.
This is stated in the Intelligence report of the Ministry of Defense of Great Britain.
Perhaps this was done due to the recent change in the level of local security threats due to the strengthening of Ukrainian long-range strike capabilities. In the past two months, the headquarters of the fleet and the main airfield of the Russian naval aviation have been attacked.
The guarantee of basing the Russian Black Sea Fleet in Crimea was probably one of the reasons that prompted President Putin to annex the peninsula in 2014. Now the security of the base is directly undermined by Russiaʼs aggression against Ukraine, according to British intelligence.