On December 15, Ukraine’s Security Service (SBU) special forces, working alongside the country’s navy, claimed the first successful strike on a submarine using an unmanned underwater vehicle (UUV), dealing a significant blow to Russia’s Black Sea Fleet. The “Sub Sea Baby” kamikaze drone reportedly hit a £300 million Improved Kilo‑class submarine moored in Novorossiysk, destroying both the vessel and the jetty where it was berthed. Although Russia officially denies serious damage, available footage indicates a substantial impact.
This latest strike follows earlier Ukrainian operations that forced the Russian navy to pull key assets from Sevastopol in occupied Crimea to Novorossiysk, a base previously considered safer from attack. With major warships and now a submarine hit in port, analysts argue there is increasingly no safety for Russian warships anywhere in the Black Sea, even as the Russian army attempts grinding advances on land. The loss of the submarine is particularly significant for the Black Sea Fleet, which has already seen two Kalibr cruise missile submarines destroyed, leaving perhaps only three in service. These Improved Kilo‑class boats were central to Russia’s long‑range missile attacks on Ukrainian cities and to its efforts to threaten commercial shipping with minimal warning.
Drones are often cited as changing the character of modern warfare. In the Black Sea, surface and now subsurface uncrewed systems have destroyed multiple Russian vessels, but in most cases the ships were anchored or alongside, making them far easier targets than maneuvering warships at sea. The relatively small size of the Black Sea means Russian bases and anchorages are under threat, not just their operating areas. Ukraine, which lacks major surface combatants, presents fewer similar targets, further skewing the tactical balance.
The Sub Sea Baby’s operation highlights the complexity of unmanned underwater attacks. To reach Novorossiysk, the UUV may have traveled on or near the surface, similar to drug‑smuggling craft, or been deployed closer in from a mothership, possibly a civilian‑looking merchant vessel. Once fully submerged, the drone would likely lose conventional communications, unless it trailed a wire back to a mother ship or a small satellite‑linked buoy outside the harbor. Without such a tether, it would need to navigate autonomously.
Underwater navigation poses a serious challenge because satellite navigation systems like GPS do not function underwater. Potential solutions include inertial navigation, scaled down from manned submarines but with possible accuracy limits over longer runs, or doppler navigation sonar, used by some special forces divers and small UUVs to track movement over the seabed. Another option is active imaging sonar to identify the submarine based on pre‑mapped harbor features, though this approach increases the risk of detection by Russian passive sensors and is error‑prone, especially for an autonomous drone.
Defending against such systems is difficult. Traditional measures like World War I‑style anti‑submarine booms and netscan be bypassed if a drone waits on the seabed until barriers are opened. Modern defenses include short‑range, high‑resolution active sonar mounted on jetties or ships, which can detect approaching divers or UUVs but still require an effective response mechanism. Small demolition charges may counter human divers carrying limpet mines, but a drone with a large warhead, on the order of 1,000 pounds, must be neutralized outside the harbor. In many scenarios, the best protection remains to be at sea and under way, where a relatively slow UUV lacks the speed of a torpedo to chase down alert warships.
Nearly four years into the war, observers note continued Ukrainian innovation in uncrewed systems and persistent Russian complacency in maritime defense. The vulnerability is not unique to Russia; current Western port infrastructure, including in the United Kingdom, is also assessed as lacking resilience against similar underwater threats. Potential targets range from naval bases to critical sites such as the Isle of Grain gas terminal in the Thames estuary, which could be approached by assets like the Russian spy ship Yantar or a nuclear‑powered mini‑sub such as Losharik, possibly deployed from a full‑sized submarine.
The attack on the Russian submarine underscores how Ukraine’s uncrewed capabilities are reshaping the maritime fight, even amid peace talks, and raises questions about how prepared other navies and port operators are to counter this remarkable new development in undersea warfare.
