Russia's secret underwater warfare: Cables in the crosshairs
The act of destroying undersea cables enables Moscow to cause significant losses to the West without crossing the threshold into war. To achieve this, Russia has been training special units for decades, skilled in underwater sabotage and attacks on critical infrastructure. One of these bases is located near the Polish border.
The tanker Eagle S, intercepted by Finnish special forces, is officially a ship under the Cook Islands flag. However, the Finns suspect that the ship was likely conducting operations on behalf of Russia.
The ship not only targeted underwater infrastructure connecting Finland and Estonia but also functioned as a floating spy platform, equipped with SIGINT (signals intelligence) gear.
The events of December 2024 represent just one episode in an undeclared war waged by states hostile to the West. Instances of civilian ships dropping anchor and dragging it along the seabed have occurred before.
The Chinese ship Yi Peng 3 damaged telecommunications cables linking Lithuania with Sweden and Finland with Germany. Another Chinese vessel, Newnew Polar Bear, damaged the Balticconnector gas pipeline and likely a telecommunications cable connecting Finland and Estonia.
Using civilian ships is just one of many options available. For years, intelligence agencies have paid particular attention to Russian "academics"—ships Russia claims are research vessels, named after esteemed Russian scientists, but are also used for seabed exploration.
Russian underwater research
Units like "Akademik Boris Petrov," "Akademik Tryoshnikov," "Akademik Nikolai Strakhov," and the latest, commissioned in 2015, "Yantar," are equipped with both manned and unmanned underwater vehicles.
An example is the AS-37 underwater vehicle, developed during the USSR era, equipped with an ARS-600 manipulator. Its two-person crew can operate at depths of up to 20,000 feet.
These ships, as civilian vessels, are equipped with the AIS (Automatic Identification System). This allows investigation of locations where critical global economic undersea cables lie, such as the North Atlantic and the eastern coast of the United States.
GUGI – deepwater saboteurs
Besides civilian vessels, Russia also possesses special forces intended for deep-sea sabotage, under the Main Directorate of Deep-Sea Research of the Russian Ministry of Defense (GUGI). Little is known about them—not even their exact founding date, believed to be in the 1960s.
GUGI was likely established in response to the SOSUS system. This secret system of underwater sensors, deployed in the Atlantic by NATO, tracked Russian submarines. These submarines had to navigate the GIUK gap—a narrow area between Greenland, Iceland, and the UK—where SOSUS enabled their detection.
To eliminate these sensors, Russia created military forces capable of carrying out reconnaissance and sabotage at great depths. Today, GUGI’s tasks include attacking undersea infrastructure and protecting Russian installations.
Fire on a unique vessel
The significance of these forces was highlighted by a 2019 fire on the AS-12 Losharik submarine. Although only 200-230 feet long, it has a nuclear propulsion system. With its external, lightweight hull, the Losharik resembles a regular submarine. However, its internal pressurized hull forms seven spherical, interconnected chambers capable of withstanding extremely high pressure, allowing it to operate at depths of up to 8,200 feet.
When the fire occurred in 2019, fourteen crew members were lost, seven of whom were commodores (equivalent to colonels), with the others being officers of at least lieutenant commander rank (equivalent to major). Two of the deceased were knights of the Russian Hero Star, the highest combat decoration in the Russian fleet.
Due to its small size, the AS-12 Losharik does not provide adequate comfort during long missions. Therefore, over an 18-year reconstruction, a large Delta IV-type vessel (K-64, renamed BS-64 Podmoskovye after reconstruction) was adapted to carry the Losharik attached to its hull.
Thanks to this configuration, the crew of the smaller vessel can experience greater comfort on the larger vessel for the bulk of the mission. According to Russian sources, renovations following the fire were completed by 2024.
The death of Hvaldimir
The threat may not only come from humans. In September 2024, in Risavika Bay in southern Norway, the body of Hvaldimir was found. Hvaldimir was a male Beluga whale (a marine mammal in the narwhal family) that surfaced a few years ago near the Norwegian island of Ingøya.
The whale wore a harness with a handle for a camera or photographic equipment, which had an inscription indicating it was from St. Petersburg. Hvaldimir was accustomed to human presence and cooperated with them, leading to speculation that the beluga might have been trained by Russians for underwater sabotage or defense.
Marine spetsnaz in the Kaliningrad region
Attacks on underwater infrastructure are not solely reserved for actions at great depths. In the Kaliningrad region, just miles from the Vistula Spit, is military unit No. 43104, the 390th Special Purpose Reconnaissance Point of the Baltic Fleet.
Alongside the center, hidden in woods yet visible by satellite in the Parusnoje area, marine divers have their own marina in Primorsk.
Equipped with fast assault boats known as Raptors, they have long posed a threat to Polish coastal infrastructure. Experts noted that for years Poland lacked suitable equipment to counter a potential small-group sabotage attack.
The situation somewhat changed in 2023, when an agreement was signed for new Griffon hovercraft for the Maritime Border Guard. Units SG-413 and SG-414 were ceremoniously commissioned into service on December 11, 2024, in Stara Pasłęka.
