The North Sea is “very unprotected” and vulnerable to possible Russian sabotage attempts on critical undersea infrastructure NATO nations heavily rely on, according to a senior Dutch military official.
Moscow’s presence in the North Sea has increased, “and so the threat as well,” said Rear Admiral Paul Flos, one of the founding members of the multinational Seabed Security Experimentation Center (SeaSEC) set up in The Hague to protect underwater infrastructure.
The North Sea is “very much” at risk from Russian activity, Flos told Newsweek, adding: “They’re not there because they like our waters.”
Critical Undersea Infrastructure
Crisscrossing beneath our oceans and seas are cables and pipelines vital to everyday life, including ensuring the lights stay on and that bank payments are processed.
Roughly 1.3 million kilometers of cables—equivalent to about 800,000 miles—are used for $10 trillion in financial transactions each day, NATO chief Mark Rutte said at the start of 2025. Undersea cables carry more than 95 percent of all internet traffic, Rutte said.
But these networks are exposed, and there are simply too many cables and pipelines to shield at any one time, said Laurence Roche, from NATO’s Italy-based Centre for Maritime Research and Experimentation.
It is “really hard to protect” critical undersea infrastructure, Roche told Newsweek.
NATO is certainly trying. In 2024, the alliance established a new United Kingdom-based center, specifically tasked with developing strategies to protect undersea networks, reporting to NATO’s Maritime Command. The alliance then launched its “Baltic Sentry” initiative to track ships moving through the Baltic Sea after several cables and pipelines were damaged or severed in late 2023.
The U.K. also launched the Proteus, a first-of-its-kind surveillance ship, to monitor underwater activities and control uncrewed underwater vehicles (UUVs) nearly two years ago.
North Sea and the Baltic
The Baltic Sea is better known than the North Sea for highlighting the vulnerability of the alliance’s critical undersea infrastructure. It is occasionally dubbed a “NATO lake,” the water bracketed by alliance members and Kaliningrad, the Russian exclave home to a formidable military footprint and Moscow’s Baltic Fleet.
NATO countries have logged a spate of incidents involving critical undersea infrastructure in the past year and a half, largely blamed on suspected sabotage by Russia in the wake of its full-scale invasion of Ukraine. Accidental damage can, and often does, happen, but officials are increasingly speaking out about attacks blamed on Moscow.
The most high-profile incidents include damage to a power cable and two communications lines in the Baltic Sea on December 25, 2024. Authorities quickly cast suspicion on the Eagle S, a Cook Islands-flagged oil tanker believed to be part of Russia’s “shadow fleet” of vessels used to circumvent sanctions.
Finnish authorities stated in mid-June that they had concluded a criminal investigation and suspected senior officers aboard the ship of “aggravated criminal mischief and aggravated interference with telecommunications” in connection with the dragging of an anchor.
Helsinki’s prosecutor general is weighing up charges, the country’s National Bureau of Investigation said in a statement.
Unnamed Western intelligence officials told the Associated Press in January that the recent damage to undersea infrastructure could be caused by anchors accidentally dragging on poorly staffed and decrepit ships.
High-voltage cables that connect electricity systems between countries, when disrupted, can cost around $14 million each day, according to the Rand think tank. The total bill for oil and gas pipelines being knocked out for months can reach the tens of billions, the organization said in June.
Admiral Sir Tony Radakin, the U.K.’s top military official, said in early 2022 that there had been a “phenomenal increase” in Russian underwater activity in the past two decades, with Moscow able to “potentially exploit the world’s real information system, which is undersea cables that go all around the world.” Former British Defense Minister Ben Wallace, still in post in 2023, stated that Russian submarines had taken “strange routes that they normally wouldn’t do,” including in the North Sea.
The Baltic and North Seas have a relatively similar shallowness, but the North Sea is more sandy where the Baltic is rocky, said Flos. “So, often, cables are easier to destroy in the Baltic than in the North Sea,” Flos said.
“But the threat is the same,” he said.
Sabotage acts like dragging anchors can only be used at certain places in the world because of the shallowness of the water, like in the Baltic, said Sidharth Kaushal, a senior research fellow for sea power at the U.K.-based Royal United Services Institute (RUSI) think tank.
To the west, several NATO countries look out onto the North Sea, including the U.K. and the Netherlands.
British Defense Secretary John Healey said at the start of the year that the Yantar, a Russian vessel spotted in the North Sea, was a “spy ship” on a mission to gather intelligence and map the U.K.’s seabed network.
The Yantar was spotted in November 2024 “loitering over U.K. critical undersea infrastructure,” Healey said. The Russian embassy in London hit back at the remarks, stating in January that the claims were “completely groundless.”
“Russia has never posed such threats,” the embassy added.
The Yantar is one of the vessels operated by Russia’s Main Directorate of Deep-Sea Research, or GUGI, a shadowy branch of the military that answers directly to the Russian defense minister and, ultimately, to Russian President Vladimir Putin.
The GUGI has a collection of submarines and surface ships, such as the Belgorod submarine, that can simultaneously carry nuclear-armed torpedoes and control small submersibles capable of diving deep underwater.
GUGI performs a variety of roles for the Kremlin, ranging from laying sensors on the seabed to surveillance, espionage, and larger strategic functions, Kaushal told Newsweek.
In the North Sea, rather than relying on anchor dragging, GUGI could use ships like the Yantar to detect critical infrastructure before deploying UUVs or remotely operated vehicles, he said.
Within GUGI’s ranks, Kaushal said, the organization has hydronauts—specialized personnel who pass “punishing” entrance criteria to steer submersibles at extreme depths. These hydronauts are pulled from Russia’s 29th Separate Submarine Division, based at the submarine hub of Gadzhiyevo in the northwestern Murmansk region and close to the Northern Fleet headquarters.
Who’s Responsible for Protecting Cables and Pipelines?
“We see you,” the U.K.’s Healey told lawmakers in January this year. “We know what you are doing.”
Flos is less sure. “What they’re doing there, nobody knows,” he said. “That’s the challenge.”
Although allied militaries can detect where Russia is poking around in the North Sea, their goals are murky, but there is “very strong evidence that they also used unmanned underwater vessels,” Flos said. Reports in British media earlier this year indicated the U.K. military had found Russian drones close to critical undersea infrastructure.
Western militaries are well-acquainted with unarmed surveillance ships like the Yantar, making this type of vessel much easier to track than some of Russia’s advanced submarines, Kaushal said.
And there has been rapid improvement on what the alliance can observe of Russia’s activity in the North Sea, even since the start of the year, Flos said. “We’re not blind anymore,” he said. Cooperation between allied countries has improved over the last year, particularly in cultivating a better understanding of how civilian ships and support vessels are utilized by the Kremlin, Kaushal said.
But a big question remains: Whose job is it to bat away Russia’s interest in the North Sea’s critical undersea infrastructure? Cables and pipelines are, the vast majority of the time, owned by private companies.
“Are the asset owners responsible? Are the nations responsible? Is the Coast Guard responsible?” Flos asked. It’s “hugely complicated,” he said, adding that the conversations were still happening.
NATO has emphasized the need to establish rapid connections with private companies and industrial players to more effectively detect threats to pipelines and cables, as well as to maintain infrastructure.
“We have to increase out cooperation with industries on all kinds of levels,” Flos said. The Dutch Navy official said he had emphasized in recent days that there needed to be more trust between governments, militaries and industry.
There does seem to be a growing consensus within NATO that protecting infrastructure used by its members is a “collective military responsibility,” added Kaushal. But it’s often opaque which powers exist to stop suspicious ships operating in international waters, he said.
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