Ukraine Hits $500M Russian Submarine with World’s First Underwater Drone Strike

Ukraine’s Security Service and Navy achieved a military milestone on December 15, 2025, launching the world’s first underwater drone strike against a submarine. Using “Sub Sea Baby” unmanned vehicles, they targeted a Russian Kilo-class vessel at Novorossiysk naval base, exposing vulnerabilities in modern naval defenses.

$400 Million Target Crippled

The Project 636.3 Improved Kilo-class submarine, valued at $400-500 million, functioned as a mobile platform for Kalibr cruise missiles with ranges up to 2,500 kilometers. Equipped with four launchers and a 52-person crew, the vessel sustained critical damage according to Ukrainian reports. Russian Black Sea Fleet officials denied any impact.

The drone slipped past multi-million-dollar harbor protections, including floating barriers and pontoon systems designed to counter Ukrainian surface threats. Navigating crowded waters, it reached the submarine at the pen’s far end. Satellite images reveal damage to a nearby pier, 20 meters from the submarine’s stern.

Pre-Strike Preparation

Ukraine executed multi-phase planning. First, the SBU destroyed Russia’s sole Black Sea Il-38N “Sea Dragon” anti-submarine aircraft at Yeysk airbase with an airburst warhead drone. Valued at $24 million, this plane provided the only detection for underwater threats near Novorossiysk, enabling the drone’s undetected approach.

Cost Asymmetry in Action

The operation highlighted stark economic disparities. Each Sea Baby drone costs $218,000-222,000, yielding a cost-exchange ratio near 2,000:1 against the $400-500 million submarine. This favors low-cost, attritable systems over high-value crewed assets, even with some mission failures.

Black Sea Fleet Retreat

The strike capped three years of Ukrainian drone campaigns that sank over 20 Russian ships—one-third of the Black Sea Fleet. Losses included the cruiser Moskva, landing ships, and the $65 million patrol vessel Sergey Kotov. These attacks prompted Russia to shift its fleet from Sevastopol, Crimea, to Novorossiysk by October 2023.

Irreparable Stern Damage

Footage captured explosions at the stern, home to propulsion, steering, and rudder systems. Even if the pressure hull held, repairs demand dry docking unavailable in the Black Sea. The Montreux Convention bars belligerent warships from the Bosphorus, blocking access to Russia’s Baltic facilities.

Halved Kalibr Threat

Russia deployed six Improved Kilo submarines to the Black Sea from 2014-2016. Post-strike, only two or three operate, cutting submarine-launched Kalibr capacity by 50-66%. Each carries four missiles, removing 16 launch tubes that targeted Ukrainian cities. Earlier strikes sank Rostov-on-Don in 2023-2024.

Mass Drone Production Edge

Ukraine produces nearly two million drones yearly across types, scaling to four million annually—exceeding any NATO nation, including the United States. Over 200 companies focus on unmanned systems, with Sea Baby in full production, sustaining operations despite losses.

Strategic Timing

The attack coincided with President Zelenskyy’s Berlin meetings on December 14-15 with Trump envoys Steve Witkoff and Jared Kushner, discussing peace terms including Donetsk withdrawals. It underscored Ukraine’s reach amid concession pressures.

Inadequate Russian Response

Russia quickly added protective barges at moorings, blocking surface and underwater paths. These measures trap ships, hindering deployments, and acknowledge failures of surface defenses against submerged incursions.

Future Horizons

Sub Sea Baby expands options, including the Kerch Bridge linking Crimea to Russia. Prior strikes with 1,100 kilograms of underwater explosives damaged supports without collapse. The drone could evade surface defenses, though payload limits raise doubts on full destruction.

Global Naval Shift

Ukraine, starting with no navy after 2014 losses, neutralized a fleet with cruisers, frigates, and submarines through drones. This “democratization of naval power” empowers non-traditional actors via specialized unmanned tools.

The strike signals submarines’ new vulnerabilities, once naval apex predators. Converging intelligence, creativity, and pressure from cheap drones challenges century-old assumptions, reshaping warfare economics and prompting global navies to adapt.