From 1 July, Sweden will step up its surveillance of Russia’s shadow fleet, introducing stricter checks on vessels navigating Swedish territorial waters and the country’s exclusive economic zone. According to Sweden’s Ministry of Justice (Justitiedepartementet), the focus will be on verifying ships’ insurance details to identify irregularities and potential sanction breaches.
The decision targets tankers suspected of circumventing EU sanctions on Russian oil by operating with unclear ownership, inadequate insurance coverage, or no registered flag. Sweden’s Justice Minister Gunnar Strömmer stated that the aim is to “deter vessels involved in the Russian shadow fleet and provide a foundation for further measures, such as sanctioning more ships.”
Denmark considers seizures and military coordination
In a parallel move, Denmark is weighing the possibility of seizing shadow fleet vessels that pose a security or environmental threat. Foreign Minister Lars Løkke Rasmussen has announced plans for a high-level meeting with representatives from Baltic Sea countries, as well as the UK and the Netherlands, to explore legal avenues for intervention. One key focus is ships sailing without proper registration or flagged status, which could justify action under international maritime law.
Rasmussen acknowledged the legal complexities but did not exclude naval interventions, saying “if vessels lack valid insurance documents and have no flag state, it is legitimate to act.”
Denmark is particularly concerned about ageing tankers transporting Russian oil through the Danish Straits, often in poor condition and without verified documentation. These ships, while exploiting maritime legal grey zones, pose risks of collisions and oil spills.
Rising tensions and NATO involvement
Efforts to disrupt the Russian shadow fleet have already contributed to rising tensions in the Baltic Sea. In recent months, Estonia temporarily detained a sanctioned vessel in poor condition, and Finland reported new patterns of military escorts accompanying Russian-linked tankers. Polish forces also recently intercepted a ship suspected of getting too close to undersea infrastructure.
Russia has sharply criticised these moves. Its ambassador to Denmark, Vladimir Barbin, condemned the initiatives as “piracy” and accused Western governments of “pushing the world towards an uncontrolled escalation.”
Barbin warned that “attempts to harm Russia‘s interests will be strongly countered,” raising fears of further provocations if shadow fleet ships are intercepted or detained.
Environmental and geopolitical risks
The expansion of the shadow fleet—a loosely defined group of vessels used to evade sanctions by masking ownership and flag status—has raised alarms not only about legal accountability, but also about maritime safety and environmental protection.
Since 2022, the European Union has imposed a price cap on Russian oil exports, prompting the emergence of these unregulated tankers. In response, NATO has increased its naval presence in the Baltic Sea to monitor the situation and safeguard undersea infrastructure, following incidents of cable sabotage linked to suspected shadow fleet activity.
Environmental experts and officials have expressed concern about “stateless” ships operating without oversight. These vessels are often poorly maintained, manned by underqualified crews, and represent a growing hazard to both shipping traffic and marine ecosystems.
According to Danish authorities, shadow fleet tankers pass through Danish waters several times a day, highlighting the urgency of developing a harmonised regional response. As Rasmussen noted, “We need a unified approach, where all countries have each other’s backs.”
A coordinated regional strategy in the making
While national measures intensify, the upcoming summit among Baltic countries, the UK, and the Netherlands could mark the first step towards a coordinated maritime enforcement framework. By aligning legal tools and operational protocols, regional governments hope to curtail the shadow fleet’s activities without escalating conflict.
The question remains how far states can go in enforcing maritime security without violating international norms or provoking military retaliation. For now, Sweden and Denmark are positioning themselves at the forefront of a developing strategy to counter the covert maritime lifeline sustaining Russia’s war economy.
