Ukraine’s Security Service, known as the SBU, claimed on December 15, 2025, that it successfully struck a Russian Improved Kilo-class submarine inside the port of Novorossiysk using an underwater unmanned system, a platform the agency refers to as Sub Sea Baby. According to the SBU, the operation was conducted jointly with the Naval Forces of Ukraine through military counterintelligence channels and caused critical damage that rendered the submarine non-operational, a claim that cannot yet be independently verified through imagery or official Russian statements. Read more...
Ukraine’s Security Service video showing a Russian Project 636.3 Varshavyanka Kilo class submarine, which the SBU claims was critically damaged in Novorossiysk by an underwater Sub Sea Baby drone during a joint operation with the Ukrainian Navy (Picture source: Ukraine's Security Service).