NATO said on Friday it would boost its presence in the Baltic Sea after the suspected sabotage this week of an undersea power cable and four internet lines, while alliance member Estonia launched a naval operation to guard a parallel electricity link.

A power cable connecting Finland and Estonia under the Baltic Sea suffered a power outage on Wednesday, prompting an investigation, according to the Finnish prime minister. The electrical transmission through the Estline 2 connection between the two European nations was cut on Wednesday afternoon local time.

Police and media reports say that Finnish authorities have detained a Russia-linked ship as they investigate whether it damaged a Baltic Sea power cable and several data cables.