Overnight December 14-15, 2025, Ukrainian forces conducted an unprecedented unmanned underwater vehicle strike against russian Project 636 Varshavyanka-class submarine, highly likely the B-271 Kolpino, located at the Novorossiysk Naval Base in the Eastern Black Sea.
A video released by the Security Service of Ukraine on December 15, 2025, shows a large explosion at the pier from the strike, in the direct vicinity of the submarine.
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The strike, utilising Sub Sea Baby drone has likely resulted in significant damage to the submarine, leaving it unable to sail of its own accord or deploy. This submarine is Kalibr missile capable platform which was used in strikes against targets in Ukraine.
As of December 18, 2025, open source reporting indicates the submarine as still docked in port in the same position it was at the time of the strike, and that other russian vessels have dispersed from the Novorossiysk Naval Base as a cautionary measure to mitigate against potential further Ukrainian strikes.
Ukraine's successful strike, penetrating Novorossiysk's multi-layered defenses, emphatically demonstrates the rapidly developing proficiency and capability of Ukraine's maritime forces, particularly utilising unmanned systems. It will highly likely significantly undermine the russian military leadership's confidence in russia's Black Sea Fleet force protection measures.
As Defense Express previously reported, on December 12, 2025, Ukrainian forces reportedly counterattacked russian forces in the north west quadrant of Kupiansk, a former rail logistics hub in Kharkiv region. In recent weeks, Ukrainian forces have conducted clearance operations in the town and contested russian logistics supply operations in the vicinity.
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