Finnish investigators probing the damage to a Baltic Sea power cable and several data cables said they found an anchor drag mark on the seabed, apparently from a Russia-linked vessel that has already been seized.

The Christmas Day cutting of four Internet cables and one power cable will cause NATO to boost its presence in the Baltic Sea. Finland last week seized the Eagle S ship, carrying Russian oil, under suspicion of being behind the cuts. “NATO will enhance its military presence in the Baltic Sea,” NATO secretary general Mark Rutte said.

Finnish investigators have linked damage to the Estlink-2 power cable in the Baltic Sea to a Russian-linked vessel, the Eagle S. Anchor drag marks stretching nearly 100 kilometers were discovered, and an investigation is underway to determine intent,

NATO member Estonia has deployed a naval warship to defend its underwater power cables after a Russian vessel allegedly cut one of the wires in yet another act of sabotage against the allied nations.

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.