- Overnight 14-15 December 2025 Ukrainian forces conducted an unprecedented uncrewed underwater vehicle (UUV) strike against a Russian Project 636 Varshavyanka-class (NATO Kilo-class) submarine, highly likely the B-271 Kolpino, located at the Novorossiysk Naval Base in the Eastern Black Sea. A video released by the Ukrainian Security Service on 15 December 2025 shows a large explosion at the pier from the strike, in the direct vicinity of the submarine.
- The strike, utilising a ‘Sub Sea Baby’ has likely resulted in significant damage to the submarine, leaving it unable to sail of its own accord or deploy. This submarine is a Kalibr missile capable platform which was used in strikes against targets in Ukraine.
- As of 18 December 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 Novorossiysk Naval Base as a cautionary measure to mitigate against potential further Ukrainian strikes.
- Ukraine’s successful strike, penetrating Novorossiysk’s multi-layered defences, emphatically demonstrates the rapidly developing proficiency and capability of Ukraine’s maritime forces, particularly utilising uncrewed systems. It will highly likely significantly undermine the Russian military leadership’s confidence in Russia’s Black Sea Fleet force protection measures.