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.

Vessels of Russia's so-called shadow tanker fleet will be boarded or put on a sanctions list if they do not provide proof of insurance, Estonia's prime minister said on Tuesday.

"Almost every month, ships are currently damaging important undersea cables in the Baltic Sea," German Foreign Minister Annalena Baerbock told Funke media group on Dec. 28. "This is an urgent wake-up call for all of us.

Multiple recent incidents involving undersea cables in the Baltic Sea were unlikely to be a coincidence, Annalena Baerbock said. She called for tougher sanctions on Russia's so-called "shadow fleet" of ships.

Following damage to an underwater power cable off Finland, German Foreign Minister Annalena Baerbock has raised alarm about the so-called Russian shadow fleet and called for further EU sanctions. "Almost every month,