Undersea data cable between two NATO countries breaks

The C-Lion1 line runs under the Baltic Sea between Finland and Germany

A “fault” has been detected on the C-Lion1 data cable connecting Finland and Germany, AP has reported, citing authorities in Helsinki.

The installation runs nearly 1,200 kilometers under the Baltic Sea, between Helsinki, Finland and Rostock, Germany. Technicians at Cinia, a Finnish state-owned data services provider, detected a disturbance during a routine check at around 4am local time on Monday.

“All the fiber connections in it are cut,” the company spokesman told Finnish media, adding that the cause of the problem is being investigated. “At the moment, there isn’t a possibility to assess the reason for the cable break, but these kinds of breaks don’t happen in these waters without an outside impact.”

Finland’s internet traffic is routing along other data cables, according to Samuli Bergstrom, head of the Cybersecurity Center at the Finnish Transport and Communications Agency (Traficom), told the broadcaster Yle.

“Disturbances occur from time to time and there can be various reasons,” Bergstrom added. “For example, they are susceptible to the weather and damage caused by shipping.”

Finland’s Security and Intelligence Service (SUPO) told Yle that it was too early to assess the cause of the cable break, noting that around 200 undersea cable breaks happen around the world every year.

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“The most common cause of cable breakage is human activity, such as fishing or anchoring,” a SUPO spokesperson said.

Finland and Estonia initially blamed Russia for an October 2023 incident that damaged an undersea gas pipeline between the two countries, until an investigation established that a Chinese cargo ship’s anchor had been responsible.

The C-Lion1 went into service in 2016, as a way to improve Finland’s data connection to central Europe. The cable itself runs close to the NordStream pipelines, which once delivered natural gas from Russia to Germany. Three out of four tubes were damaged by sabotage in September 2022, while the fourth has never been activated, due to Berlin’s refusal to certify its operation. 

No one has taken responsibility for the blasts that disabled the pipelines. Investigative journalist Seymour Hersh has pointed the finger at the US and Norway. Several Western newspapers have claimed that a group of Ukrainians carried out the bombing, with or without Kiev’s knowledge or approval.