Europe's militaries have been working together for years to keep an eye on what Russia is up to at sea

• The Nord Stream pipeline sabotage in September drew new attention to maritime threats in Europe.

At the end of September, the Nord Stream 1 and 2 natural gas pipelines connecting Russia to Germany were damaged in an apparent act of sabotage, with some officials blaming Russia.

Although the pipelines were not in use— Nord Stream 1 was shut down in March by EU sanctions against Russia, and Nord Stream 2 wasn't yet operational—the incident highlights the risks to underwater infrastructure.

"There is a vulnerability around anything that sits upon the seabed, whether that's gas pipelines, whether that's data cables," Adm. Ben Key, first sea lord and chief of the British naval staff, told reporters after the incident.

As the world's reliance on underwater infrastructure, including telecommunications cables and gas pipelines, increases, the European Union's militaries have been developing assets to counter attacks on such vulnerable infrastructure.

Underwater dangers

Much of the world's underwater infrastructure is in international waters and can stretch for hundreds or even thousands of miles, which creates legal and operational challenges to protecting it.

Even before the war in Ukraine, Western officials had grown worried about increasing activity by Russian ships and submarines around underwater cables crossing the Atlantic.

The US Navy admiral in charge of NATO's submarine force said in 2017 that the alliance was "seeing Russian underwater activity in the vicinity of undersea cables that I don't believe we have ever seen."

"Russia is clearly taking an interest in NATO and NATO nations' undersea infrastructure," the admiral said at the time.

The Russian Main Directorate for Deep Sea Research is responsible for conducting underwater surveillance and research.

The nine nuclear-powered submarines attached to the directorate can conduct deep dives, and some of them can deploy smaller purpose-built underwater vessels that could tap or attack underwater infrastructure.

Russia has invested heavily in both conventional and special-purpose submarines, many of which are based on the Kola Peninsula, home to Russia's powerful Northern Fleet.

"To target the cables covertly, in deep water where they would be harder to repair, specialist submarines are required. Russia is unique in having a large fleet of these," naval warfare researcher H I Sutton told The Barents Observer in 2018.

Europe's response

The European Union is making a concerted effort to minimize the threat to sea and coastal infrastructure through its Permanent Structured Cooperation, or PESCO, framework.

PESCO, which was launched in 2017, is an effort to promote collaboration among EU members on common defense and security projects. It aims to increase European defense integration while addressing areas of concern.

PESCO currently supports eight maritime projects aimed at defending European countries against maritime threats, the first of which began in 2018.

Its headline maritime project is the development of a European patrol corvette, which is led by Italy with a number of major European defense firms participating. The corvette is designed for use in the Mediterranean and will have anti-submarine warfare and other capabilities. It is expected to enter service in 2026.

To counter submarine threats, EU members are also developing a semiautonomous surface vehicle for use in coastal areas but also at sea as part of a naval group.

The vehicle will be able to perform a variety of missions, including anti-submarine and anti-surface warfare, as well as intelligence, surveillance, and reconnaissance operations.

EU members are also upgrading and developing more surveillance capabilities for harbors and other critical maritime areas that will use a network of land-based, maritime, and aerial platforms to allow EU members to detect and respond to maritime threats faster.

Further, a Portugal-led project is developing an unmanned anti-submarine system to protect "high-value infrastructure as well as sea-based energy systems."

The Portuguese navy has considerable experience with maritime drones and has been hosting the annual REPMUS exercise, which focuses on integrating unmanned and manned maritime assets.

Nevertheless, preventing an attack on underwater infrastructure is challenging because of the vast area that EU militaries have to cover, so the EU has also sent a political message to Russia about the consequences of such interference.

Following the Nord Stream disruptions, Ursula von der Leyen, president of the European Commission, warned that "any deliberate disruption of active European energy infrastructure is unacceptable and will lead to the strongest possible response."

Constantine Atlamazoglou works on transatlantic and European security. He holds a master's degree in security studies and European affairs from the Fletcher School of Law and Diplomacy. You can contact him on LinkedIn.