Russia’s ‘ghost fleet’ turns key NATO waterway into frontline of hybrid war

What once looked like an ordinary shipping route between Sweden and Denmark is now emerging as one of Europe’s most sensitive flashpoints.

According to El País, the narrow Øresund Strait has become a testing ground for Russia’s expanding campaign of hybrid warfare against NATO, involving suspected sabotage, covert maritime operations and so-called “ghost ships” moving through the Baltic Sea.

Strategic waters

Only four kilometers separate the Swedish city of Helsingborg from Denmark’s Helsingør, with ferries, trucks and commuters crossing the strait daily as if it were routine infrastructure rather than a geopolitical fault line.

But the Øresund is one of the Baltic Sea’s most important exits into the Atlantic Ocean, alongside Denmark’s Great Belt and Little Belt straits. Nearly all maritime traffic entering or leaving the Baltic passes through the corridor.

“For centuries, control of the Øresund meant control of access to the Baltic Sea,” Helsingborg resident Per Svensson told El País.

“These waters have always been ordinary for us, not a border. Now everything seems to have changed,” he added.

Shadow operations

Swedish Foreign Minister Maria Malmer Stenergard said ships linked to Russia’s so-called “shadow fleet” are now frequently seen moving through the region.

According to Nordic authorities, at least 292 Russian-linked vessels crossed the area in 2025 after departing ports in the Baltic Sea.

The ships are often old tankers operating under opaque ownership structures and foreign flags that change regularly, allowing Russian oil exports to bypass Western sanctions tied to the war in Ukraine.

Swedish officials also told El País that intelligence assessments indicate some vessels may carry armed contractors connected to paramilitary groups with Kremlin ties, giving the ships what one official described as “a military aura.”

NATO’s new frontier

Russia’s invasion of Ukraine dramatically reshaped security calculations across northern Europe, pushing Finland and Sweden into NATO and transforming the Baltic Sea into what defense analysts increasingly describe as a “NATO lake.”

That shift has made strategic chokepoints like the Øresund significantly more important to the alliance.

According to Elisabeth Braw of the Atlantic Council’s Center for Transatlantic Security Strategy, the Baltic has become one of the Kremlin’s primary laboratories for hybrid warfare.

“There are no fleet battles or classic naval engagements,” Braw said, describing tactics that include undersea sabotage, interference with navigation systems, covert operations and attacks on maritime infrastructure.

Rising fears

Regional authorities have recorded at least 11 major incidents involving damaged undersea cables and critical infrastructure since October 2023, according to Estonian intelligence cited by El País.

While investigations have rarely formally blamed Moscow, several cases involved vessels linked to Russian ports or the shadow fleet.

One example involved the cargo ship Fitburg, detained by Finnish authorities in December 2025 after it was suspected of damaging telecommunications cables between Finland and Estonia.

Sweden has since expanded Coast Guard powers to monitor vessels transiting its territorial waters and exclusive economic zone.

“We are not at war, but we are not at peace either,” Prime Minister Ulf Kristersson said.

Old tensions return

Residents in Helsingborg say the growing military presence has changed the atmosphere in the coastal city.

“I always thought we would never experience conflict again, but nothing seems certain anymore,” local teacher Karin Akerman told El País.

Across the Skåne coastline, Cold War-era bunkers overlooking the Øresund are once again being viewed as symbols of a region preparing for a more dangerous future.

Sources: El País, Estonian intelligence reports

This article is made and published by Asger Risom, who may have used AI in the preparation