Germany and Finland have said they are “deeply concerned” following reports that an undersea communications cable linking the two countries had been severed, with suspicions raised of “hybrid warfare by malicious actors”.
The 729-mile C-Lion1 fibre-optic cable between Helsinki in Finland and Rostock in Germany went offline in the early hours of Monday morning, with Cinia, the line’s Finnish operator, saying it was almost certainly the result of an “external force”.
It follows reports of damage to a separate undersea communications cable between Lithuania and Sweden – near to the one that was severed in the Baltic Sea – on Sunday.
In a joint statement on Monday, the Finnish and German foreign ministers said: “Our European security is not only under threat from Russia’s war of aggression against Ukraine, but also from hybrid warfare by malicious actors. Safeguarding our shared critical infrastructure is vital to our security and the resilience of our societies.”
While a physical inspection of the severed cable has yet to take place, the sudden outage suggests that the cable was completely severed by an outside force, Cinia’s chief executive, Ari-Jussi Knaapila, told a press conference.
“These kinds of breaks don’t happen in these waters without an outside impact,” a Cinia spokesperson told local media.
Cinia said it was working with authorities to investigate the incident and that repairs typically took between five and 15 days.
Swedish public service broadcaster SVT reported that Swedish authorities were also investigating damage to a 218-mile communications cable running between Lithuania and Sweden, close to the one that was severed.
“It is absolutely central that it is clarified why we currently have two cables in the Baltic Sea that are not working,” Carl-Oskar Bohlin, minister of civil defence, told SVT.
There have been fears of sabotage to undersea infrastructure ever since the unexplained explosions of the Nord Stream gas pipelines between Russia and Germany in 2022, which German prosecutors are still investigating.
In October 2023, a natural gas pipeline and two data cables between Finland and Estonia were badly damaged. It was later concluded that the incident had been caused by a Chinese container ship dragging its anchor, although authorities did not state whether the damage was believed to be accidental or intentional.
Nato member countries have increased monitoring of the tens of thousands of kilometres of cables and pipelines in the North and Baltic Seas in the years since the Russian invasion of Ukraine.
In September, US officials told CNN that increased Russian military activity had been detected around key undersea cables.
“We are concerned about heightened Russian naval activity worldwide and that Russia’s decision calculus for damaging US and allied undersea critical infrastructure may be changing,” the official said. “Russia is continuing to develop naval capabilities for undersea sabotage mainly thru GUGI [General Staff Main Directorate for Deep Sea Research], a closely guarded unit that operates surface vessels, submarines and naval drones.”