Sweden’s navy has said Russia is running a military operation in the Baltic Sea that appears designed to protect the vessels commonly described as Moscow’s “shadow fleet” — tankers used to keep oil moving despite Western restrictions.

In remarks reported by Sweden’s public broadcaster SVT, the navy said the activity has been visible in two forms: Russian naval units maintaining a recurring presence in specific sea areas close to major shipping lanes, and uniformed personnel seen or reported aboard some shadow-fleet tankers.

Commodore Marko Petkovic, head of operations in the Swedish Navy, told SVT that Sweden had both observed and received information indicating that “people in uniform” were on board some of the relevant vessels. According to SVT’s reporting of Swedish military assessments, some of those individuals are believed to be armed and may be connected to private security companies rather than regular Russian forces.

SVT reported that information about uniformed personnel aboard shadow-fleet ships had circulated during the autumn, and that the Swedish Navy now confirms it has comparable reporting.

Swedish military sources quoted by SVT described the maritime posture as a “fairly constant presence” in several designated zones adjacent to sea routes used by commercial shipping. The pattern, they said, resembles an operation built around monitoring and deterrence in a limited number of locations rather than manoeuvre warfare across the wider Baltic.

The Swedish assessment comes as Baltic and Nordic governments continue to treat sanction evasion, maritime safety, and critical undersea infrastructure as linked security issues. NATO, which Sweden joined on 7 March 2024, has increased its attention to the Baltic Sea’s vulnerability to destabilising acts against cables and pipelines.

NATO’s “Baltic Sentry” activity, launched in January 2025, was presented by the alliance as a measure to strengthen protection of critical infrastructure and improve the ability to respond to incidents at sea. Swedish officials have in recent months publicly tied the shadow-fleet phenomenon to wider maritime situational awareness requirements, including monitoring unusual behaviour by civilian-flagged vessels in sensitive areas.

The term “shadow fleet” is used by European governments, analysts and the shipping industry to describe tankers whose ownership, insurance, flagging and tracking practices can obscure the origin and destination of cargoes. These vessels have been associated with practices such as frequent flag changes and the manipulation or disabling of AIS transponders used for vessel tracking — conduct that has also drawn regulatory and enforcement responses.

The core economic driver is the oil trade. The G7 and partners introduced a price-cap system and related maritime-services restrictions after Russia’s full-scale invasion of Ukraine, aiming to constrain revenues while keeping global supply flows stable. In September 2025 the UK lowered its crude oil price cap from $60 to $47.60 per barrel, according to government guidance; the European Commission has described a parallel reduction and a mechanism for future adjustments within EU sanctions policy.

Against that backdrop, EU measures have increasingly targeted vessels and intermediaries linked to sanction evasion. On 15 December 2025, the EU adopted additional sanctions aimed at individuals and companies accused of facilitating Russian oil shipments through high-risk and irregular maritime practices associated with the shadow fleet, according to Reuters and the EU’s Official Journal-based listings cited by the agency.

The Swedish Navy did not publicly identify specific ships or provide imagery of the reported uniformed personnel. The description nevertheless adds detail to a growing body of Baltic reporting in which the shadow fleet is treated not only as a sanctions issue but also as a security and governance challenge: a high volume of ageing tankers operating in confined waters, combined with ambiguity over responsibility, inspection, and response in the event of an incident.

Separately, the shadow fleet has been drawn into the war’s kinetic maritime dimension. On 10 December 2025 Ukrainian sea drones disabled a tanker described as part of Russia’s shadow fleet in the Black Sea, in an incident that maritime security sources said added to war-risk costs for shipping.