An undersea fiber optic cable between Latvia and Sweden was damaged on Sunday, likely as a result of external influence, Latvia said, triggering an investigation by local and NATO maritime forces in the Baltic Sea.

A subsea cable connecting Latvia to Sweden’s Gotland island is the latest cable to be damaged in the Baltic Sea. Owned by Latvia’s State Radio and Television Centre (LVRTC), the cable’s Ventspils–Gotland segment was damaged early on January 26, at depths of 100m.

RIGA, Latvia (AP) — Latvian Prime Minister Evika Siliņa said Sunday that her government has reached out to Sweden and other Baltic Sea allies in NATO for assistance as it investigates the cause of damage to an underwater data cable running to Sweden.

After a fiber optic cable was damaged near Sweden, Latvia sent a patrol boat to inspect a suspicious vessel in the Baltic Sea. Sweden later said it seized a vessel believed to have carried out the sabotage.

A subsea data cable between Latvia and Sweden was damaged early Sunday, sparking a criminal investigation, a third such incident in the Baltic Sea in the past three months.