Russia has assembled a fleet of hundreds of vessels to covertly ship its oil. With so many ships at sea, the idea of using some to cause havoc may be proving irresistible to the Kremlin.

Finland says a ship affiliated with Russia's "shadow fleet" is linked to a 60-mile-long anchor drag mark on the seafloor. A power cable in the Baltic Sea was severed last week.

The damaged cable is one of several recent incidents in the Baltic Sea under investigation as possible acts of sabotage.

A court in Finland denied a request to release an oil tanker, which is suspected to have damaged an undersea power line and four telecommunications cables in the Baltic Sea, according to a Reuters report.