TROMSØ, Norway — In late January, an unexpected vessel arrived at this Arctic port: a Russian-crewed Norwegian cargo ship, the Silver Dania, detained under suspicion of sabotage. The coast guard escorted it here following an urgent missive from Latvia: An undersea fiber optic cable between the Baltic country and Swedish island of Gotland had sustained serious damage. The Latvian authorities suspected the Silver Dania may have been to blame. But after a day’s investigation, Tromsø police released the 113-meter reefer.
Investigators had “secured what we see as necessary,” police attorney Ronny Jørgensen told reporters. “The investigation will continue but we see no reason for the ship to remain in Tromsø.”
Any results will likely take a long time to produce; deliberate sabotage is extremely hard to prove. Still, just a few months ago, Latvia likely wouldn’t have tried at all. That changed in December, when Finland made international headlines by seizing a tanker carrying 35,000 tons of oil from St. Petersburg from Estonia, accusing it of deliberately damaging a crucial cable under the Baltic Sea. The following day, Finnish Prime Minister Petteri Orpo announced a criminal investigation into the vessel, the Eagle S, and its possible link to Russia’s “shadow fleet”: an armada of sanction-evading tankers quietly delivering fossil fuels to the globe.
“These shadow ships are pumping money into Russia’s war chest so that Russia can continue its war against Ukraine,” he said. “We cannot and will not look away. We will not accept this.”
After the Kremlin’s 2022 full-scale invasion of Ukraine, Western sanctions restricted crude oil shipments from Russia and imposed strict limits on the price of other fossil fuels. That was intended as a huge blow; around half the country’s revenue comes from oil and gas sales. But according to US intelligence, Russia has since brought a fleet of more than 600 decommissioned, uninsured vessels back online, registered under non-Western flags.
Thanks to deceptive practices such as obscured ownership structures, falsified locations and ship-to-ship transfers of goods, the fleet has continued to bring what’s probably an immense amount of oil and gas to global markets at above-sanction prices. The Centre for Energy and Clean Air, a Finnish think tank, estimates that Russia has earned over $70 billion from shadow shipments since 2022.
The difficult-to-trace ships are likely serving another of Russia’s aims: “hybrid warfare,” or cyber, information and infrastructure attacks that fall short of formal military escalation. In 2023, I wrote about the growing threat of Arctic hybrid warfare for Foreign Policy, including undersea infrastructure attacks. Such suspected actions have significantly increased in both the Arctic and Baltic regions since 2021.
In April that year, more than four kilometers of Norwegian armed forces surveillance cables in the Norwegian Sea were cut and mysteriously disappeared. In February 2022, just weeks before Russia invaded Ukraine, another cable connecting Svalbard to the Norwegian mainland suddenly went offline. In the Baltic Sea in 2023 and 2024, 11 more cable and three gas pipe disruptions were linked to shadow fleet tankers. (A few were blamed on Chinese vessels, a possible sign of Moscow’s deepening ties with Beijing.)
If you ask Russia, the incidents weren’t attacks at all. Shortly after the Silver Dania’s detainment, the Russian Embassy in Norway called for an inquiry. Moscow’s denials expose a massive Western vulnerability: Undersea infrastructure maps are commonly accessible to help ships avoid damaging them. But they can just as easily enable attacks. With one strategic drag of an anchor, millions of people can instantly lose power. Repairs can take months and investigations span years, posing Western countries a dilemma.
“Not only is direct attribution extremely difficult, which makes effective deterrence even more challenging, but such tactics fall beneath the threshold of armed conflict,” University of Colorado at Boulder political scientist Gabriella Gricius wrote for The Jamestown Foundation in February. “Russia can simultaneously employ plausible deniability and avoid outright war while also causing serious disruption to Western societies.”
Even if it can be proved, marine sabotage is tough to penalize. The main international maritime legal framework, the 1991 “Law of the Sea” (The United Nations Convention on the Law of the Sea), is a bundle of rules and agreements so complicated that one expert made me promise not to write about it without speaking to her first. Because the arrangement would require a dispatch of its own, I’ll emphasize just a few key distinctions.
Beyond 12 nautical miles from shore, one leaves territorial waters and enters the “high seas,” which permits free navigation, flyover, fishing and cable-laying to all. On these legally loose waters, ships fall under the legal jurisdiction of their own states, so it’s common to register under “flags of convenience,” or low-regulation countries. More than half the world’s merchant ships were internationally registered in that way as of 2024. And despite its name, the Law of the Sea is a treaty, not a law—so enforcing its many agreements about spying, resource extraction and pollution depends largely on goodwill.
Still, the ocean is vast and dangerous, creating an interdependence that helps sustain that goodwill. In 2022, when most cooperation between Western states and Moscow broke down, coast guard, search and rescue and fisheries agreements were among the few to survive. Lately, however, growing sabotage, espionage and illicit shipping have been testing decades-long agreements. Maritime military tensions are also rising: The Kola Peninsula—an inlet of the Arctic Ocean that Russia shares with Norway and Finland—is Russia’s fastest-militarizing zone and home to most of its nuclear ships. In 2023, Russia’s coast guard stepped up cooperation with China’s, another move that appeared close to signifying an outright military alliance.
In Tromsø, a city built around a crucial northern port, such threats feel uncomfortably close. The vast majority of what we call the “Arctic” is water, encompassing the northernmost reaches of the Atlantic, Baltic Sea and Pacific. On the ocean floor, thousands of miles of cables and pipelines keep lights on and communities online. At the surface, thousands more miles of shipping superhighways keep the global economy afloat. Spanning the planet’s northernmost ocean, you’ll find the globe’s shortest trade routes—but also the shortest path for an intercontinental nuclear missile.
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On a windy day in February, snow dusted the docks of Tromsø harbor and a low cloud bank obscured the mountains across the fjord. It was below freezing but the incessant bray of seagulls—which went silent in deep winter—signified the coming spring. Close to the town center, the only visible ship was of the cruise variety: a glittering multistoried structure bound for glaciers further north. But from the north to the south end of the island, dozens of ports hosted other ships of all kinds. On that very ordinary afternoon—as I discovered in the port’s public online log—the city was hosting two cruise ships, a pollution-control vessel, three fishing boats and a Norwegian ship of unknown category.
Just a week earlier, the Silver Dania’s brief detainment brought international drama within a mile of my house. In an otherwise remote city beyond the reach of Amazon Prime deliveries, the highly trafficked waterfront is a constant reminder of this locality’s inherent globalism, and a corresponding tie to economic and geopolitical forces much larger than ourselves. Cities like mine are only as safe as our ports. Yet citizens don’t always have a say over who is granted entry.
In September 2024, a controversy rocked Tromsø when a damaged ship carrying potentially explosive cargo was granted “safe refuge” in the harbor. The Ruby, which had departed from Russia, was carrying 20,000 tons of ammonium nitrate—about seven times more than the amount that leveled large parts of Beirut in 2020, killing 218 people and injuring about 7,000 more. The ship, crippled by damage to its hull and propeller, arrived in an industrial port on the north section of the island—just down the road from the largest major hospital in northern Norway.
The Ruby’s brief harbor represented international maritime law at work: Under the Law of the Sea, Norway is obligated to allow safe refuge for ships in distress. But at the time, Tromsø’s local papers and cafes alike were buzzing with questions: Who really owned the Maltese-flagged ship and why was it carrying so much potentially deadly cargo? Where and how was it damaged? And why on Earth, with so many other ports in Norway, did the authorities permit its arrival in this highly populated city? After only a day, the police ordered the ship to leave and it moved along to a smaller northern port.
The growing threat of warfare—hybrid or otherwise—can also put municipal and national security interests at odds. Before I moved here, my own nation caused a different harbor hangup: In September 2023, when a US nuclear-powered submarine docked in Norway for the first time in history, it came to Tromsø. Understandably, local schools, hospitals, businesses and citizens didn’t particularly want it there.
For those close to the sea—the Arctic, Baltic and beyond—“security” is a double-sided coin. The port of Tromsø is a crucial part of the Norwegian economy, with billions of dollars’ worth of seafood, fuel and other goods regularly passing through these waters. Similarly, Baltic Sea cables are a central link in the European energy grid. But that marvelous connectivity also exposes us to ill-intentioned actors who may, sailing under some dubious flag, cut a crucial cable or deliver threats directly to our doorsteps.
Tactics intended to deter such threats—for instance, granting American nuclear submarines entry to our ports—risk backfiring. That is the “security dilemma” coined by the American scholar John Herz in 1950: When a state acts to protect its own security, rivals almost always respond in kind, creating a vicious circle that quickly degrades the security of all.
It is, Herz argues in his paper “Idealist Internationalism and the Security Dilemma,” a timeless human problem. Look at any chapter in history, he wrote 75 years ago, and you’ll find the same “heartbreaking plight in which a bipolarized and atom bomb-blessed world finds itself in today.”
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On January 14, NATO announced the deployment of the “Baltic Sentry”: a brand-new fleet of warships, aircraft and drones policing Baltic waters for shadowy behavior. Two days later, I spoke to Caroline Hoefsmit, a lead officer of NATO’s Maritime Command.
“We have ships out there now patrolling, and hopefully by being there, by being present, we can help deter these threats to our critical infrastructure from happening again,” she told me. “But we can’t totally prevent it.”
Should NATO’s armed patrol suspect a ship, it would need legal justification to seize it. And the fallout from Finland’s December seizure of the Eagle S, which seemed a turning point, has proved how slippery maritime law can be on that front. Within days, Finland had to release the ship because it couldn’t produce evidence linking the vessel to the damage. Soon, the Emirati owner said he would seek legal recourse because Finland seized the ship outside its own territorial waters.
So far, no shadow ship has faced repercussions for either shipment or sabotage. But they may soon. As I write in mid-February, four Baltic EU member countries—Finland, Estonia, Latvia and Lithuania—are meeting in Brussels to discuss joint policies to increase enforcement. They are exploring two potential routes using existing maritime law, POLITICO Europe reported. The first is environmental: The tankers, most of which are older than the 20-year age limit to ship crude oil, are defect-prone and run a high risk of damaging the environment. However, because shadow tankers are usually uninsured, they exist outside the legal structure often used to penalize environmental damage.
The second option is to invoke international counter-piracy laws that police attacks at sea. But those laws were designed to address ships assaulting other ships, not subsea cables, and it’s not clear if the law can stretch far enough to cover such infrastructure. In case existing rules prove insufficient, POLITICO quoted its sources as saying, those countries are discussing jointly imposing new national laws. They might include, for instance, requiring tanker operators to pick from a prescribed list of credible insurers—paving a possible route to at least legally detain them.
Would Russia appreciate such legal innovations? The moves may actually risk escalating hybrid warfare to direct conflict. In February, Alexei Zhuravlev, the deputy chair of Russia’s parliamentary defense committee, said that “any attack on our carriers can be regarded as an attack on our territory, even if the ship is under a foreign flag.” He made clear that seizing any craft would prompt “retaliatory measures” including “boarding Western ships in the Baltic but also active measures from our Baltic fleet, which is certainly no match for the Baltic countries’ array of small boats.”
As John Herz predicted 70 years ago, it’s a textbook security dilemma. How, then, to move forward? In a 1978 paper, “Cooperation under the Security Dilemma,” the American political scientist Robert Jervis argued there’s a way to mitigate the dilemma’s worst consequences: a strategy of reassurance, in which rivals stick to old agreements, forged in times of lower tension, at all costs.
“[S]tates interested in stability are usually wise to respect the status quo and adhere to prior agreements,” he wrote. “Blatant violations erode trust, and trust once lost is hard to regain.”
Russia has long violated that trust, including by the full-scale invasion of Ukraine and more shadowy antagonism at sea, one could argue. But yet another dilemma underlies the West’s next steps. Any one wrong move could mean subjecting your own citizens to potentially avoidable conflict—and, in doing so, sacrificing their security for its own sake.
Top photo: Norwegian search and rescue crew rehearses an emergency at sea in Tromsø in February. After Russia invaded Ukraine, marine search and rescue cooperation was one of the few partnerships Western countries, including Norway, maintained with their eastern neighbor
