Intruder Alert: Ports Face a Range of Underwater Threats

On December 15, 2025, footage from a hacked security camera at Russia’s Novorossiysk Naval Base captured a powerful underwater explosion rocking a berthed Kilo-class submarine. The Ukrainian Security Service (SBU) subsequently took responsibility for the attack, claiming that it had been carried out by a previously undisclosed uncrewed underwater vehicle (UUV), “Sub Sea Baby.” While Ukraine has been quite open about its efforts to deploy combat UUVs (an armed “Marichka” may have been used in an underwater strike on the Kerch bridge in June of 2025), the Novorossiysk attack represents the first known instance of a UUV conducting a submerged strike inside a defended naval port.

Beyond the implications for Russia’s Black Sea Fleet, the episode highlights a broader, urgent reality: ports and harbors are increasingly vulnerable to hostile underwater uncrewed systems. Advances in autonomy, navigation, and energy storage have enabled relatively small underwater platforms to operate at ranges and with precision that would have been difficult to achieve only a decade ago. At the same time, the lines separating mines, torpedoes, and UUVs are blurring as these systems increasingly converge in both capabilities and mission sets. For ports and naval facilities, where ships, logistics infrastructure, and critical undersea assets are