The country’s prime minister said the incident, the latest in a series of disruptions to undersea infrastructure, underscored the danger of a so-called Russian shadow fleet.

Finnish police said on Thursday they are investigating whether a foreign ship was involved in the damage of an undersea power cable connecting Finland and Estonia following a sudden outage on Wednesday.

An undersea power cable that runs between Finland and Estonia was disconnected on Christmas Day. Finland is pretty sure that Russia is to blame. On Thursday, Finnish authorities boarded an oil tanker that is part of Russia’s “shadow fleet” used to dodge sanctions and that just so happened to be spotted passing over the EstLink 2 underwater cable as it stopped working,