Danish naval patrol vessels monitoring a Chinese bulk carrier suspected of involvement in damaging undersea cables.MIKKEL BERG PEDERSEN/Ritzau Scanpix/AFP via Getty ImagesUndersea cables between Finland-Germany and Lithuania-Sweden were cut, potentially sabotaged.The incident is one of a number of similar incidents in recent years, highlighting the vulnerability of these lines.NATO is enhancing surveillance and coordination to protect critical underwater infrastructure.Last month, an underwater data cable between Finland and Germany and another between Lithuania and Sweden were discovered cut within a day of each other.