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 Secretary-General Mark Rutte says the military alliance will step up patrols in the Baltic Sea area as Finnish investigators work to establish whether a ship linked to Russia sabotaged undersea cables there this week.

NATO allies met on Dec. 30 to address the security of critical infrastructure in the Baltic Sea, following damage to undersea cables connecting Estonia and Finland several days earlier.