London
CNN
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On Sunday, an undersea cable ferrying data between Sweden and Latvia was damaged, most likely as a result of an external force, Latvia said.

This is just the latest in a string of incidents since late 2022 causing damage to Europe’s infrastructure that crisscrosses the bottom of the Baltic Sea — pipes carrying natural gas and cables transporting electricity and data.

Such incidents have become more frequent over the past couple of years, raising suspicions they are the result of sabotage and triggering a flurry of investigations by European officials — with some openly pointing fingers at Moscow.

Russia has denied allegations of any involvement.

So far, the impact on Europe’s natural gas, electricity and data flows has been fairly limited. But a concerted attack on data cables could paralyze many nations’ communications networks, jeopardizing hospital surgeries, police responses and more.

If Russia is indeed to blame for some of the incidents, they are Moscow’s way of showing its power to disrupt European infrastructure, said Sophia Besch, senior fellow at Carnegie Endowment for International Peace.

It’s “about intimidation, undermining resolve, creating a general sense of fear and instability in populations, and showing that they could do something,” she told CNN.

Last week, the Russian embassy in London said NATO — a defensive alliance between North American and European countries — was using the “fictitious pretext of the ‘Russian threat’” to beef up its naval and air force presence in the Baltic.

The statement followed an announcement by NATO of a new mission to strengthen the protection of critical infrastructure in the Baltic. As part of that mission, the alliance has deployed sub-sea drones.

Whether the damage has been accidental or intentional, the incidents have exposed one of Europe’s vulnerabilities, signaling, in the words of one expert, “a new frontier” in its security. Europe is “to a significant degree, dependent on this type of infrastructure,” said Georg Zachmann, a senior fellow at Brussels-based think tank Bruegel, adding that he finds the current situation “very worrying.”

The first major incident occurred in late 2022, months after Russia launched its full-scale invasion of Ukraine. A series of explosions rocked the Nord Stream 1 gas pipeline delivering Russian gas to Europe, as well as Nord Stream 2. Neither of the pipelines was transporting gas at the time of the blasts, though they still held the fuel under pressure.

Investigators found evidence of explosives at the sites, leading Swedish prosecutors to conclude that the blasts were caused by an act of sabotage. And last August, German authorities issued an international arrest warrant for a Ukrainian man suspected of carrying out the explosions.

Whoever was behind the blasts, Besch at Carnegie Endowment for International Peace said they were a “wake-up call” for Europe. “Ever since then we have seen Europeans invest in their own security underseas,” she noted.

The second incident took place in October 2023 when a natural gas pipeline between Finland and Estonia, called the Balticconnector, began to leak.

Then, in November last year, two undersea internet cables — one connecting Sweden and Lithuania, and the other Finland and Germany — were cut. In a joint statement, the foreign ministers of Finland and Germany said the incident “immediately raises suspicions of intentional damage,” adding that European security was under threat from “hybrid warfare by malicious actors.”

A few weeks later, on Christmas Day, a power cable connecting Finland and Estonia failed. The following day, Finnish authorities boarded and detained the Eagle S — a tanker carrying oil from Russia to Turkey — on suspicion it had damaged the cable by dragging its anchor.

Assigning blame for each incident is a tricky, diplomatically fraught task.

In September, two US officials told CNN that the United States had detected increased Russian military activity around key undersea cables.

But hard evidence implicating Moscow is difficult to come by, and US officials familiar with an initial assessment of November’s incident in the Baltic told CNN at the time that there were “no indications of nefarious activity” involving the two cut internet cables.

“The challenge is (that) a lot of this can be wrapped up in what one might describe as plausible deniability — some people would call it implausible deniability,” said Nick Childs, a senior fellow for naval forces and maritime security at the International Institute for Strategic Studies.

He added that the Baltic was a “very congested, very crowded waterway,” making it difficult to both spot and prove suspicious activity. Still, he said, “a lot of fingers are pointing at Russia” for some of the incidents.

Some are pointing specifically at Russia’s so-called “shadow fleet” — aging tankers, many with opaque ownership structures, transporting Russian oil for export to avoid Western sanctions.

Dovilė Šakalienė, Lithuania’s defense minister, told CNN in an interview last week that this shadow fleet was “cutting our power cables… cutting our data cables… cutting our pipelines” and that the damage was likely deliberate.

“If something happens once, it’s an accident. If something happens twice, it’s a coincidence. But, if it’s three times or more, I think all our common sense screams at us: Hello, really?” she said.

Besch, at the Carnegie Endowment for International Peace, notes that Europe’s cable infrastructure has high levels of “redundancy,” meaning that, when one cable fails, whatever it is transporting can be re-routed through another.

However, some islands close to Scotland and Norway are more vulnerable, she said. “There are only one or two cables — if you cut them, you have a problem.”

Repairs to undersea networks can also be costly and take months.

Even small outages could impact online shopping and home deliveries, and deny tens of thousands access to their favorite shows and movies.

“Safeguarding our infrastructure is of utmost importance,” NATO Secretary General Mark Rutte said earlier this month.

This is “crucial” for both energy supply — whether from power cables or pipelines — and internet traffic, he said, noting that more than 95% of that traffic globally is carried via undersea cables.

CNN’s Clare Sebastian and Vasco Cotovio contributed reporting.