Defense Express reported the information.A Ukrainian underwater drone strike on a Russian Kilo-class submarine at Novorossiysk naval base has effectively removed the vessel from combat operations for the remainder of the war, according to military analysts familiar with Russia's severely limited repair capabilities in the Black Sea region.The attack, carried out jointly by Ukraine's Security Service and Naval Forces using a Sub Sea Baby underwater drone, struck the submarine's stern section, causing significant damage to critical components including rudder controls and propeller shafts. While such damage would typically require extensive but achievable repairs, Russia's inability to conduct submarine maintenance in the Black Sea theater makes recovery of the vessel highly improbable.The situation mirrors the fate of the B-237 Rostov-on-Donu, another Black Sea Fleet submarine that was first damaged in September 2023 and later sunk in August 2024. After the initial strike while in dry dock at Sevastopol's shipyard, Russian forces spent nine months attempting basic repairs before the vessel was destroyed in a follow-up missile attack.Russia's submarine repair infrastructure in the Black Sea is concentrated exclusively in occupied Sevastopol, where facilities are inadequate for complex maintenance work. Before the full-scale invasion, Moscow routinely sent Black Sea submarines to the Kronstadt Naval Plant in the Baltic Sea for major overhauls.However, the Montreux Convention now prevents Russian warships from transiting between the Black Sea and Mediterranean, effectively trapping damaged vessels. While Russia theoretically could transport smaller ships through the Don-Volga-Baltic waterway system, the Kilo-class submarine's 20-foot draft far exceeds the canal system's 11-foot depth limit, making such a transfer extraordinarily complex and potentially unfeasible.Military officials have not yet confirmed which specific submarine was hit—either the B-265 Krasnodar, B-268 Veliky Novgorod, or B-271 Kolpino—but all three represent significant assets for Russia's already diminished Black Sea naval presence.