By Bojan Pancevski

The North Atlantic Treaty Organization mounted its first coordinated response to the suspected sabotage campaign against critical infrastructure, after another underwater data cable was severed in the Baltic Sea.

NATO vessels raced to the site of a damaged fiber-optic cable in Swedish waters on Sunday morning, where a trio of ships carrying Russian cargo, including one recently sanctioned by the U.S., were nearby. All three vessels are now being investigated as part of a probe into suspected sabotage of the fiber optic cable , according to several European officials. One ship was detained Sunday.

The incident is the latest in a string of alleged underwater attacks in the region that prompted NATO to announce earlier this month the formation of a surveillance mission called Baltic Sentry. It includes regular naval patrols, as well as enhanced drone, satellite and electronic surveillance of Baltic areas that are crisscrossed by critical infrastructure such as data and power cables, along with gas pipelines and offshore wind farms.

Western officials have said they suspect Russia is fighting a shadow war against the West. Russia has denied it is behind such an effort.

"We have seen elements of a campaign to destabilize our societies. Through cyberattacks, assassination attempts, and sabotage -- including possible sabotage of undersea cables in the Baltic Sea," NATO Secretary-General Mark Rutte said earlier this month.

Evidence gathered so far in the Baltic investigations hasn't been conclusive enough to result in prosecutions or arrests, officials familiar with the investigations said.

Latvia dispatched its navy to the site of the incident Sunday, while the Swedish coastguard detained one of the three ships within hours of the incident, according to Latvian and Swedish officials. A Dutch warship was also involved in the operation to combat alleged attacks on deep- sea assets.

The Latvian officials said the latest incident damaged a cable between Sweden and Latvia that belongs to Latvia's public broadcasting company. The cable suffered "external damage" but the outage didn't affect end users, the company said.

Latvia's navy identified three vessels that were close to the damage site as potential culprits, the Latvian officials said.

One of them, the bulk carrier called Vezhen, which is registered in Malta and had departed the Russian port Ust-Luga on Friday, was detained and boarded by Swedish police on Sunday, officials said.

The owner of Vezhen, a Bulgarian company called Navigation Maritime Bulgare JSC, said that the incident took place during bad weather and there was no indication that the crew acted with intention to cut the cable.

"I do not in any way assume that this was sabotage or any other similar action on the part of our crew," Alexander Kalchev, chief executive of Navigation Maritime Bulgare JSC, told the Bulgarian news agency BTA.

The two other ships under investigation are Pskov, a Barbados-registered tanker that carries Russian liquefied natural gas and that has been sanctioned by the U.S. in response to Russia's war in Ukraine, and Silver Dania, a Norwegian-flagged cargo ship that recently departed Russia.

The Norwegian owner of Silver Dania agreed to order the ship into a Norwegian port, where it will be boarded by investigators, after an intervention by Latvia's Foreign Minister Baiba Braze who called her Norwegian counterpart Espen Barth Eide on Sunday, according to the Latvian government. The ship's captain is cooperating with the probe, the officials said.

Barbadian authorities haven't so far agreed to cooperate with the investigation into the Pskov, according to one senior European official familiar with the probe, and the ship, whose captain has declined requests to halt its course, is continuing its journey to St. Petersburg.

Pskov was sanctioned by the U.S. on Jan. 10 because it is suspected of being part of the so-called shadow fleet that helps Russia transport oil and gas. One of the Latvian officials familiar with the investigation said that the Pskov was twice inspected externally from afar and there was no apparent damage to its anchor or hull.

Under international maritime law, a ship in international waters is under the jurisdiction of the country of its registration, and can only be boarded by foreign law enforcement with explicit permission of its owner or flag country. The captain of the Pskov cited international law of the sea as he argued in a radio exchange against an official request to steer his ship into a port in Finland, the nearest NATO nation relative to its current location, according to a person familiar with the investigation.

The Baltic, home to Russia's rare ice-free commercial ports, is one of the busiest trade corridors in the world. As the U.S. and its western allies tightened sanctions against Russian energy exports, Moscow started deploying warships to escort its shadow fleet tankers in the Baltic, sometimes including ships carrying powerful missiles, according to several European officials.

In December, Finland detained a vessel called Eagle S, an oil tanker belonging to Russia's shadow fleet that is registered in the Cook Islands, on suspicion that it had deliberately used its anchor to cut a power cable connecting Finland and Estonia.

In a midnight raid, Finnish special forces dropped from a helicopter onto the deck of Eagle S and captured the ship and its crew, which have since been detained in a Finnish port.

In November, an investigation was launched against a Chinese bulk carrier called Yi Peng 3, which cut two data cables in the Baltic after dragging its anchor for several hours, according to investigators. The vessel was loaded with Russian fertilizer. The probe continues.

Write to Bojan Pancevski at bojan.pancevski@wsj.com

(END) Dow Jones Newswires

January 27, 2025 11:22 ET (16:22 GMT)

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