Swedish police said on Friday they were investigating a suspected case of sabotage of an undersea telecoms cable in the Baltic Sea, and the country’s coast guard deployed a vessel to the area where multiple seabed cables have been damaged in recent months.

The Baltic Sea region is on alert and the NATO alliance has boosted its presence after a series of power cable, telecom and gas pipeline outages since Russia invaded Ukraine in 2022. Most have been caused by civilian ships dragging their anchors.

Finnish telecom operator Cinia said on Friday that it had detected minor damage on its C-Lion1 undersea fibre-optic link connecting Finland and Germany but that there was no impact on the cable’s functionality.

Swedish police were investigating the matter because the breach had occurred in Sweden’s economic zone, police spokesperson Mathias Rutegard told Reuters.

“The preliminary investigation relates to suspected sabotage,” Rutegard said.

It is the third time in recent months that Cinia’s C-Lion1 cable was damaged, after it was completely severed in November and December last year.

The Swedish coastguard said it had sent a vessel to help investigate the incident off the island of Gotland.

Sweden’s prosecution authority said it was not involved in the investigation of the cable breach.

Prime Minister Ulf Kristersson said the government was being briefed and that damage to any undersea infrastructure was particularly concerning amid the current security situation.