The Eagle S was seized by Finnish authorities on Thursday after the EstLink 2 undersea power cable linking Finland and Estonia was damaged on Christmas Day, along with fiber-optic internet connections.

Shipping website Lloyd’s List, citing a source familiar with the vessel, reported that hi-tech devices for recording radio frequencies were brought on board in suitcases and operated by the crew.

“They were monitoring all NATO naval ships and aircraft,” the anonymous source, who had provided maritime services to the Eagle S, told the specialist publication.

They added that it was unusual for a commercial tanker to carry such equipment, claiming that its power consumption had led to several blackouts. The devices, they said, were offloaded for analysis when the vessel docked in Russia.

Another ship, the Swiftsea Rider, had similar technology installed, the source said. They also alleged that the Eagle S had dropped “sensors-type devices” in the English Channel.

Power link inoperational ‘until August’

The damage to the EstLink 2 electricity lines caused a power outage in Estonia on Christmas Day and the country’s authorities say the connection might not be fully operational again until August.

NATO announced on Friday that it would enhance its military presence in the area, while Estonia launched a naval operation to protect the remaining power cables linking it to Finland, known as Estlink 1.

Nations along the Baltic Sea are on high alert for potential acts of sabotage following a string of outages of power cables, telecom links and gas pipelines since Russia’s full-scale invasion of Ukraine in 2022.

Russia has regularly denied any involvement in suspected sabotage in the region.

The Eagle S is believed to be part of Moscow’s “shadow fleet”—the name given to vessels that, among other functions, transport Russian oil in defiance of Western sanctions.

Finnish investigators believe the seized ship, which is registered in the Cook Islands, may have caused damage to the undersea cables by dragging its anchor along the seabed. The country’s police force said officials are looking into suspected aggravated criminal mischief.

“Investigative measures have been taken on the vessel, including collecting material,” said Detective Chief Inspector Sami Paila. 

“Analysis of that material is already on the way. Interviewing members of the crew has also been in the focus of the investigation.

“Although we needed to move fast at the start of the criminal investigation, it is ultimately a question of a challenging and time-consuming process.”

Lloyd’s List reported that the ownership of the Eagle S is vague because of complex corporate structures. The publication tried to contact the tanker’s operator, Peninsular Maritime India Private Limited, but received no response.