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Baltic Tensions Rise as Russia’s ‘Phantom Fleet’ Strikes Cables

As the threat of hybrid attacks in the Baltic Sea intensifies, NATO states are responding with Operation "Baltic Sentry."

Words: Théodore Donguy
Pictures: Théo Prouvost
Date:

In the dark waters of the Baltic Sea, an orange, torpedo-like object plunges into the depths. It is not a weapon but one of the reconnaissance underwater drones deployed by the Jotvingis, the flagship of the Lithuanian Navy.

The military uses this device to inspect the condition of undersea cables, which have been repeatedly targeted in hybrid attacks over the past months. “We can descend up to 20 meters (65 feet). Then, using a sonar system, we scan and receive data on the state of cables within a designated area,” explains Captain Arunas, who asked to be identified only by his last name.

In the background, the Jotvingis almost disappears into the Baltic fog. It’s time for the small vessel to return to the main ship, where the data will be analyzed. That day, no damage was reported on the submerged infrastructure lying 50 meters (over 160 feet) below.

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The drone is equipped with a sonar capable of scanning an area of 250,000 square meters. ©Théo Prouvost

The crew quickly resumes its hunt for any suspicious vessel. Through Captain Arunas’ binoculars, visibility is nearly zero. “One kilometer, no more.” The weather conditions make patrolling difficult for the fifty sailors. Their mission, as part of NATO’s “Baltic Sentry” operation, is to prevent hybrid threats.

Later, a large black silhouette emerges from the gray winter horizon. The command bridge remains quiet — the container ship has just left Klaipeda, Lithuania’s third-largest city and the Navy’s home port. “No need to inspect this one; they responded to our radio check earlier,” the captain explains.

Off the Lithuanian coast, the military ensures for days that no vessel engages in threatening activity within the country’s exclusive economic zone. “It’s like our backyard. If we sense a threat, it’s bad for our people, and we will respond,” the captain states, gazing at the horizon.

On this freezing January morning, guard shifts on deck feel interminable. Upon rotation, sailors quickly retreat inside the ship, where officers closely monitor the radar for any suspicious activity.

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If the Jotvingis and the dozen other Lithuanian Navy vessels remain on high alert, it is because tensions in the Baltic Sea are at historic levels. Since Russia’s full-scale invasion of Ukraine in 2022, these shallow waters have become the stage for hybrid warfare, with attacks strongly suggesting Russian involvement.

In the officers’ lounge, Admiral Giedrius Premeneckas clarifies: “We are facing hybrid scenarios that were not on our radar a few years ago. Underwater infrastructure is the first target.” Bordered by nine countries, the Baltic Sea is crisscrossed with electrical and communication cables.

Four incidents have occurred in the past three years, all attributed to Russia’s shadow fleet. These ships transport hydrocarbons that fuel Moscow’s revenues. Often aging, poorly insured, operating outside legal oversight, and flying various foreign flags, they allow Russia to bypass Western oil sanctions.

The most recent incident took place on Jan. 26, 2025. A fiber-optic submarine cable linking Ventspils, Latvia, to Sweden’s Gotland Island was damaged. Swedish authorities detained the Michelis San, a bulk carrier sailing under the Maltese flag.

A month earlier, on Dec. 25, 2024, the Estlink 2 power cable between Finland and Estonia was severed. Finnish authorities reported that an oil tanker, the Eagle S, dragged its anchor along the seabed for 100 kilometers (62 miles) before it latched onto the cables. The tanker, flying the Cook Islands flag, was described by Finnish customs officials as part of Russia’s shadow fleet.

Carrying oil and gas in defiance of international sanctions, the vessel remains docked along the Finnish coast, awaiting investigative results. Fingrid, Finland’s state electricity operator, estimates the damaged cable’s repair could last until late July and cost tens of millions of euros.

On Nov. 17, Lithuania also fell victim to sabotage. The 218-kilometer BCS fiber-optic cable linking Sweden’s Gotland Island to Lithuania was severed. Just hours later, on Nov. 18, at 4:04 a.m., the C-Lion1 cable connecting Helsinki, Finland, to Rostock, Germany, was also damaged.

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Since 2023, all Baltic Sea nations except Russia have joined NATO. As hybrid attacks escalated, the eight leaders of the Alliance met at the Baltic Allies Summit in Helsinki on Jan. 14, this year, announcing a set of measures to strengthen security and prevent future sabotage.

As part of Operation “Baltic Sentry,” NATO is deploying frigates, maritime patrol aircraft, and a small fleet of naval drones to the region.

In some cases, the Jotvingis directly monitors the shadow fleet, though it does not intercept vessels. Admiral Premeneckas explains the procedure: “We track them on radar, then conduct a visual inspection at sea. We question the captain and transmit all information to the authorities.”

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Several Lithuanian soldiers are constantly monitoring the horizon. © Théodore Donguy

These authorities are NATO command centers. NATO and the EU have compiled a list of vessels suspected of operating under the Kremlin’s control. “It’s a special list, shared by the European Union and NATO member states: the ‘Shadow Fleet’ list. Every inspection involves checking if the vessel is included,” the admiral explains. Currently, “nearly a hundred” ships appear on this list, though many more are believed to be part of the shadow fleet. 

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Wearing his highest-ranking naval uniform, the admiral also highlights the environmental risks posed by the shadow fleet. These ships are often dilapidated, underinsured, and poorly maintained. “The Baltic is a confined sea, so a large oil spill could cause an environmental disaster.”

On Jan. 10, 2025, the Eventin, a ship carrying 99,000 tons of oil, was secured by three German assistance vessels to prevent a spill. Following this incident, German Foreign Minister Annalena Baerbock accused Russia of “endangering” European security “not only with its war of aggression against Ukraine but also with… decrepit tankers.”

Charlie Edwards, senior advisor at the International Institute for Strategic Studies (IISS), explains, “Through all these actions, Russia is intensifying its hybrid war in Europe, multiplying operations on an ever-shifting front.”

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Captain Arunas supervises the fifty soldiers aboard the Jotvingis. © Théodore Donguy

Between 2022 and late 2024, nearly 60 hybrid warfare operations conducted by Russian intelligence — mainly the Russian military intelligence agency (GRU) and Russian Federal Security Service, (FSB) — are estimated to have targeted Europe. Moscow’s hybrid tactics range from physical sabotage to cyberattacks and electoral interference.

As the third anniversary of Russia’s invasion of Ukraine approaches, its hybrid warfare continues to escalate. That day on the Jotvingis, no shadow fleet vessel was detected. But Captain Arunas remains alert: “Every Russian operation will have a response from us.”

Cover image: Lithuanian soldiers board the Jotvingis. ©Théo Prouvost

Théodore Donguy

Théodore Donguy is an independent journalist based in Paris. He covers human rights and war in Eastern Europe.

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