ROSTOCK — In the Baltic Sea, the real war is what you cannot see.
Johan-Elias Seljamaa grips the controls tightly, trying to steady himself on the bridge of the Sakala. Heavy waves roll through the Gulf of Finland; the Estonian Navy minesweeper keeps lurching upwards and then crashing down again, rising and falling for a whole hour. Finally, Captain Seljamaa reaches the East-West channel, the main traffic artery: to the East lies the Russian metropolis of St. Petersburg, far to the West lies the gateway to the North Sea and, from there, to the global market.
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Freighters and tankers move along here like cars on a highway — more than 500 ships each week. Seljamaa, the deputy commander of the Estonian Navy, wears the blue coveralls of the armed forces, his sleeves rolled up, four stripes of rank displayed proudly on his chest. At the channel, the Sakala slows down.
Seljamaa glances at the radar screen: every ship on the waterway appears as a small green dot, each one labeled with a name or a call sign: Rocmar, Megastar, Warship. Any one of them could be the enemy Seljamaa is searching for.
Since December, Seljamaa’s units have been patrolling an undersea cable known as Estlink 2. It lies deep on the seabed and supplies Estonia with electricity from Finland. “That’s why we are here,” Seljamaa shouts over the roar of the ship’s engines. “We have to show our presence.” Presence against an invisible enemy.
When your anchor falls
On Christmas Day 2024, the oil tanker Eagle S, carrying 35,000 tons of gasoline from Russia, dropped anchor here in the Gulf of Finland, moved forward, and damaged the Estlink 2 cable, barely a few centimeters thick. Shortly afterward, the Finnish Coast Guard stopped the Eagle S, escorted it to port, and impounded the ship, which sails under the flag of the South Pacific Cook Islands. Later, the Eagle S‘s anchor was recovered from the seabed.
Seljamaa shrugs as he talks about the incident. “In all my years at sea, I have never experienced anything like this.” He pauses before adding, “When your anchor falls into the water, you notice it.”
“Every one of us is a defender of our country”
The Finns’ tough response is part of a broader strategy that emphasizes quick action against suspected Russian-backed attacks on infrastructure. Former Finnish President Sauli Niinistö drafted a report on civil and military resilience specifically for the EU. Speaking to Die Zeit in an interview, the former head of state said: “In Finland, the military and private sector work hand in hand. Every one of us is a defender of our country.”
For most Germans, the Baltic Sea means vacation: a sparkling playground, a sailing paradise, a place associated with beach chairs, ice cream, and sunburn. But the Baltic is becoming something very different. Here, NATO and Russian interests collide more and more — politically, economically, and militarily. Ever since Russia invaded Ukraine, the 400,000-square-kilometer sea has become an area of rising tension, the stage for a hybrid conflict that could flare up at any time.
Russian military jets repeatedly buzz NATO airspace over the Baltic. Just at the end of March, German Eurofighters intercepted a Russian reconnaissance aircraft east of Rügen, flying without a transponder signal and ignoring radio calls. Just before the New Year, Dutch planes forced a Russian jet fighter, reportedly carrying supersonic missiles, to turn back over the sea.
Critical systems, largely unprotected
The situation in the Baltic is “tense,” says German Rear Admiral Stephan Haisch, who monitors the region for NATO. Every ship moving through these waters could pose a threat. And it is not just a matter of cut power lines or severed internet cables on the seabed. What if a fully loaded tanker catches fire off the Bay of Kiel and blocks the German Navy base? What if a leaking oil tanker triggers an environmental disaster? What if a freighter crashes into the Øresund Bridge between Copenhagen and Malmö, cutting off the strait? What if one of the wind farms in the Baltic is attacked? These are still just scenarios, but the danger is all too real.
From a strategic point of view, the Baltic Sea is a potential battlefield. A future theater of war.
A conflict here would spell disaster for both sides. The coastal states around the Baltic account for over 10% of world trade. They produce oil and generate electricity. Communication lines, power cables, and pipelines crisscross the seabed, connecting nations and fueling economies. Yet these critical systems are largely unprotected, easy targets for sabotage.
For Russia too, the Baltic Sea is vital. The open route across the North Sea to the Atlantic remains one of its key links to the outside world. Historically, Russia has fought bitter wars over it, especially against Sweden, once the dominant Baltic power. Between the 16th and 18th centuries, Swedish kings and Russian tsars waged brutal battles for control of the sea. It was not until the Great Northern War from 1700 to 1721 that Tsar Peter I finally broke Sweden’s grip and secured Russia’s free passage.
Putin’s floating time bombs
It is a cold, gray day in the Gulf of Finland; the water, the sky, even the hull of the Estonian minesweeper Sakala all blend into the same bleak shade. An officer switches on the ultrasound scanner used to check the submarine cables: nothing unusual. Captain Seljamaa watches every ship moving west from St. Petersburg or coming in from there. Tankers, trawlers, container ships, general cargo vessels — they all follow the tightly marked shipping lanes. Everything seems routine. Until the Suez Ice Supreme appears on the radar. The 20-year-old tanker, sailing under the Liberian flag, has a history of transporting Russian oil: is the Suez Ice Supreme one of the infamous shadow tankers?
After Putin’s invasion of Ukraine, the West tried to choke Russia’s raw material exports. A price cap was slapped on Russian oil, and ships carrying overpriced oil were barred from Western insurance. The hope was simple: no insurance, no shipping, no exports. But the Kremlin adapted. Russia assembled a “shadow fleet,” snapping up around 400 old tankers worldwide. Today, about 30% of Russia’s crude oil still leaves through the Baltic ports of Ust-Luga and Primorsk; for refined products like diesel, the share is likely even higher. Put all that together, and roughly 10% of Russia’s state revenue flows through this sea. Putin cannot do without the Baltic.
The real owners hide behind shell companies
The shadow fleet sails under flags from Panama, Liberia, Malta, or the Marshall Islands. They switch flag states regularly, sometimes even repainting ship names. There is little to no proper insurance. The real owners hide behind shell companies scattered across the United Arab Emirates, China, Turkey, and even EU countries like Greece. These aging ships are floating disasters waiting to happen, threatening to poison the Baltic’s narrow waters.
And sometimes, these ghost tankers have other missions. They pull crazy maneuvers, stray from shipping lanes, and often show up near a broken submarine cable. Was it an accident? An attack? A test?
Seljamaa’s sailors zoom in on the Suez Ice Supreme with a camera. At least its anchor is properly stowed. It is sailing at a normal pace. Seljamaa can only stand by and watch as the sanctions regime is allegedly sidestepped. “The legal limits for us are very clear,” he says.
The sea has its own rules. And those rules make it nearly impossible for Western democracies to crack down on Russia’s shadow fleet. Nele Matz-Lück, a professor of international law at Kiel University, knows all about it. From her office near the Kiel Canal, she has spent 25 years studying everything that happens at sea: piracy, migration, deep-sea mining, and now sabotage.
“There is nothing you can do”
“We can do little more than watch sabotage happen,” she says. Any ship outside the 12-mile coastal zone has the right to passage. Only the ship’s flag state has jurisdiction. That is the rule under the UN Convention on the Law of the Sea, written at a time when merchant ships were not being used for covert ops. “You can shadow ships, you can request they stop dragging their anchors,” says Matz-Lück. “But if the captain ignores you, there is nothing you can do.”
That applies even to tankers like the Eagle S, which wrecked the Estlink cable. It applies to the Yi Peng 3, which snapped the internet link between Rostock and Helsinki last November. It applies to all those creaking, aging tankers, barely seaworthy, hauling Russian oil, gasoline, and diesel to the Suez Canal, India, and China to fund Putin’s war chest. “Whoever masterminded this shadow fleet,” says Matz-Lück, “knew exactly what they were doing.”
The soldiers at the Commander Task Force Baltic (CTF Baltic) stationned at Hanse Barracks in Rostock know about it. Since October 2024, under Bundeswehr command, they have kept an eye on the Baltic region for NATO. Whenever a Russian sub cruises near a cable off Gotland, or a spy ship circles a wind farm, or a corvette leaves Kaliningrad, the word gets to Stephan Haisch. The Rear Admiral commands the CTF. Satellite, sensor, aircraft, naval, and intelligence data from across NATO flows to him and his team. Haisch works in a sleek, four-story building near the Ostseestadion, home of third-division soccer club Hansa Rostock. The modern white block stands in stark contrast to the surrounding gray barracks from the Nazi era.
“We want the enemy to know: we see you”
Rear Admiral Haisch greets us in a plain conference room. He speaks in a calm, steady voice. His job is to make sure nothing that happens on or under the Baltic Sea goes unnoticed. And he wants Russia to know it too. “We are making it clear that we are watching,” he says. “We want the enemy to know: we see you.” The enemy is Russia.
Russia’s attacks on Ukraine and on seabed infrastructure have convinced neighboring countries that they must work together more closely. This led to the creation of CTF Baltic in 2024, with its multinational headquarters now under Haisch’s command.
Baltic Sea surveillance is about much more than just ghost tankers. Russia’s Baltic Fleet, one of its four major fleets, is based in Baltiysk, Kaliningrad. It fields destroyers, frigates, corvettes, subs, and landing ships. Kaliningrad itself is a heavily militarized outpost between Poland and the Baltics. Russia sees any attempt to cut off Kaliningrad’s supply routes from the mainland as an act of war.
War preparations
Alongside warships and shadow tankers, Russian spy ships also patrol the Baltic. Disguised as research vessels, they survey the seabed, gathering data for potential military operations. Experts call it “shaping the battlefield,” a term that in German is translated more bluntly: preparing for war.
In February, Vice Admiral Jan Christian Kaack, head of the German Navy, warned of a “test of our resilience.” Speaking at the “Navy Talks” in Berlin, Kaack pointed to “suspicious maneuvers by Russian-controlled ships near critical infrastructure,” an “increasing number of anchor losses,” attempted sabotage of naval vessels, and “attempts to engage uniformed soldiers returning home.” Russia, he said, is trying “to unsettle our society and our alliance. And perhaps laying the groundwork for future military action.”
Asked about the situation, CTF chief Haisch says: on the surface, Russian units are behaving normally. But, he adds, “I have the feeling they are testing us.” Odd maneuvers are meant to probe NATO’s reactions, he says. When a research vessel circles a wind farm, when spy ships drift along a pipeline, when a tanker anchors where it should not, the Russians are gathering intelligence: How fast do NATO forces react? How quickly does the coast guard respond? How soon does a recon plane take off?
Constitutional states are not helpless
Haisch’s playbook for the Baltic: show the enemy you are watching, to discourage them. If necessary, lend a hand. If one of his units spots a merchant ship drifting anchorless or behaving oddly, they will radio in. “We offer to send an expert aboard, maybe to check the engine or go over the charts.” Once on board, they can get a better look.
Watch, assist, and hope: those are the tools at hand against Russia’s provocations. The hybrid war in the Baltic pits dictatorship against democracy, lawless opportunists against rule-followers. Yet even constitutional states are not helpless.
On the night of January 9, the German Federal Maritime and Hydrographic Agency in Cuxhaven got an emergency call. A tanker was adrift, powerless, with no functioning engine or rudder, being tossed by gale-force winds and four-meter waves. The Eventin, flying the Panamanian flag, was drifting toward Rügen and risked running aground. Aboard were twenty sailors, a Russian captain, and nearly 100,000 tons of contraband Russian oil. A disaster loomed.
Two emergency tugboats set out to help; a helicopter flew specialists aboard. There was no running water, and the mostly Asian crew had stomach bugs. Rescuers fought for hours. They could not pull the ship clear. In the end, they towed the tanker into Sassnitz, into calmer waters and safety.
And into German territorial waters, where different rules apply.
A Blow to Putin
Ronald Damp, the harbor master in Sassnitz, sits at his desk, with large windows looking out over the calm sea. “There it is,” the 61-year-old says, pointing at the tanker. It is anchored about five kilometers offshore. Customs vessels patrol nearby, tourists peer through binoculars, and even with the naked eye, one can spot the Eventin‘s white bridge and black hull.
Damp has been harbor master for a decade and a seafarer for thirty years. He wears black jeans and a technical jacket, resting his hands on his hips even while seated. Two months after the near-catastrophe, in March, the Eventin’s crew approached him. They were confused, unsure whether they would get paid, receiving no updates. Only uniformed officers, some armed, were allowed on board. The crew has since been replaced.
While moored off Sassnitz, the Eventin became a political hot potato. Berlin was abuzz with phone calls; EU authorities got involved. Finally, the decision came down: German customs seized the tanker and its cargo, not with commandos, but with a legal order.
It was a blow to Putin; no Baltic country had ever moved this decisively against the shadow fleet. Russia lost not just a ship, but 100,000 tons of oil worth 40 million euros. Just before Easter, the Eventin will be moved to the Nordperd anchorage for dangerous goods. The next steps for the tanker will now be decided in court. Its owners are challenging the seizure. The fate of the Eventin and its cargo will be decided not by soldiers, but by judges at the tax court in Greifswald.
