The Enemy Below: Fighting against Russia’s Hybrid Underwater Warfare​

By Hotaka Nakamura

Nine months have passed since underwater explosions in the Baltic Sea caused ruptures in the Nord Stream pipelines, exacerbating anxiety stemming from the war in Ukraine and soaring energy prices. Though the investigation is yet to implicate the culprit behind these attacks, many have pointed to Russia as the mastermind behind these attacks – for good reason. Sabotage is a common method from the Kremlin’s playbook of hybrid warfare, and within the Ministry of Defense exists an organization with precisely the tools and mandate to conduct these submarine covert operations. While Russia has been investing heavily into building its submarine fleet, Western defense officials are only starting to sound the alarm about the potential risks to critical underwater infrastructure. In light of the war in Ukraine and NATO’s northward expansion, the United States and its transatlantic allies must make a concerted effort to reinforce its subsea defenses against Russian hybrid tactics.

What is GUGI?

Also known as “Military Unit 40056,” or “GUGI” – the acronym of its Russian name Glavnoye Upravlenie Glubokovodnykh Issledovannii – the Main Directorate of Deep-Sea Research is an elusive branch of the Russian Ministry of Defense. Though this agency operates independently of the other armed forces, its vessels and personnel are often attached to fleets of the Russian Navy.

GUGI’s function that has been gaining the most attention is its capability of conducting covert espionage and sabotage operations underwater. In recent years, many countries have started to realize the vulnerabilities and potential threats to critical maritime infrastructure, such as pipelines, wind farms, and submarine cables, that they rely on for energy, data, and communications. In this regard, Russia becomes a natural, primary suspect in incidents of damage to underwater infrastructure, given its predilection for hybrid warfare tactics to exploit its adversaries’ weak points.

Vulnerabilities to critical underwater infrastructure

Undersea cables are a prime example of strategic vulnerability for the United States and Europe. Russia is far less reliant on these cable networks and is continuing to invest in its capabilities to disrupt communications and data traffic. These data super-highways are indispensable across multiple sectors of society, providing global connectivity in financial transactions, communications, and other forms of data. Because NATO member countries also rely heavily on these networks for diplomatic, intelligence, and military communications, concerns among defense and security officials over the potential exploitation of these vulnerabilities by Russian sabotage attacks are well-founded, especially during the ongoing war in Ukraine.

One of GUGI’s assets capable of conducting seabed warfare is Yantar, a “special purpose ship” for “oceanographic research” – a euphemism for underwater covert operations. The elusive vessel has been spotted periodically around the world, from the Caribbean Sea to the Persian Gulf, and most recently, along the coast of Ireland near the AEC-1 and Celtic-Norse submarine cables. With submersibles capable of operating at a depth of 6,000 meters, Yantar has been suspected of surveying infrastructure and equipment along the seabed, such as submarine cables and underwater sensors.

However, it is important to note that GUGI does not have sole mandate over underwater covert operations. The Russian Navy’s Intelligence Directorate has its own assets capable of conducting espionage and sabotage operations at the direction of the Main Intelligence Directorate (GRU). In April 2023, Swedish, Danish, Norwegian, and Finnish broadcasters published a report on a joint investigation that tracked a fleet of Russian ships in the Nordic Seas, including the Admiral Vladimirsky, a vessel operated by Russian naval intelligence that sailed near wind farms and Swedish training areas. The line separating each agency’s duties is unclear, and this ambiguity goes to a larger issue of attribution, which the Nord Stream incident has proven to be a major challenge to defending submarine infrastructure. Without understanding the scope of the agencies’ responsibilities and capabilities, formulating a strategy to counter their operations becomes more onerous.

Efforts towards improved defense

The latest U.S. National Strategy for the Arctic Region, released last October, listed strategic competition against Russia and China in the Arctic as one of its pillars, demonstrating ongoing threats to U.S. interests. In 2021, the U.S. Cable Security Fleet was established as part of a critical infrastructure protection program using commercial, U.S.-flagged cable ships crewed by trained Merchant Mariners. Though currently facing funding challenges, this program is a good first step in providing protection and repair services for commercial submarine infrastructure.

Additionally, the U.S. Navy will build a new, modified Virginia-class submarine “mothership” designed to carry UUVs, remote operated vehicles (ROVs), and special operations submersibles. Though fueled by strong support in the Navy and Congress, this $5.1 billion submarine will likely not be operational for another 13 years. Gen. Glen VanHerck, Commander of U.S. Northern Command and NORAD, has lamented the current lack of resources, training, and organization that are vital for effective defense of U.S. interests in the Arctic region. It is clear more must be done.

Further, Finland’s ascension to and Sweden’s pending ascension to NATO could bring the transatlantic military alliance into GUGI’s crosshairs even more. Until this year, Russia enjoyed an advantage in the Arctic Circle, dominating the region with over three times the number of bases compared to NATO. With limited domain awareness and visibility into Russian activities, some Arctic experts claim that it would take a decade for NATO to catch up. Meanwhile, Russia continues to bolster its defenses in the Arctic to protect its economic interests and military posture, especially as NATO’s northern expansion increases the Kremlin’s threat perception along its northwestern flank.

On the international level, both NATO and the European Union have stepped up their efforts to address their vulnerabilities underwater. In February, NATO established the Critical Undersea Infrastructure Coordination Cell to facilitate information sharing within the alliance and with private industry and improve its readiness and response to threats to undersea infrastructure. Finland’s accession to NATO opens another potential theater of confrontation with Russia, but it also could enhance the alliance’s posture in the Arctic and contribute to its toolbox of sea surveillance, intelligence gathering, and underwater autonomous systems.

So far, the war in Ukraine does not seem to have any noticeable effect on Russia’s capabilities in hybrid underwater warfare, and its submarine fleet still presents a substantial threat to the security of the United States and its allies. Given this persistent threat, NATO members should invest in their own Cable Security Fleets, conduct joint exercises to improve readiness, and strengthen information sharing. As long as Russia remains an adversary, NATO must invest more in counter capabilities to anticipate, protect, and respond to Russian covert operations under the sea.

Hotaka Nakamura is a recent graduate of the Security Studies Program at Georgetown University’s Walsh School of Foreign Service. He has previously contributed to the Middle East Institute’s Frontier Europe Initiative and The Diplomat.

The views expressed in this piece are the sole opinions of the author and do not necessarily reflect those of the Center for Maritime Strategy or other institutions listed.