The French Navy sent the surveillance vessel Dupuy de Lôme to the Baltic Sea on May 16, 2025, to monitor Russian activity, including so-called "shadow" tankers used to circumvent Western sanctions, the British newspaper The Times reported. The operation, launched amid rising tensions in the region and increased patrols by Russia's Baltic Fleet, is aimed at intercepting radio signals and collecting data on the movements of vessels involved in Russian oil exports. The mission, classified as secret, underscores NATO's desire to strengthen its control over the Baltic sea lanes, where Russia maintains a significant presence.

The 101-metre-long Dupuy de Lôme is equipped with advanced electronic surveillance systems to track communications and ship movements. France deployed it in the Baltic Sea for the first time, Reuters reported, in response to Russia’s increasing use of a “shadow fleet” of older tankers flying the flags of third countries such as Liberia or Panama to transport oil in defiance of sanctions. These vessels, which often switch off their transponders, complicate monitoring and pose environmental risks due to their outdated equipment, Bloomberg reported. In 2024, the “shadow fleet” carried about 60% of Russia’s oil exports by sea, according to Lloyd’s List, making it a key target for NATO intelligence.

The mission began amid heightened activity by the Russian navy. According to The Times, on May 17, off the coast of Denmark, near the island of Fehmarn, Dupuy de Lôme found itself close to the Baltic Fleet corvette Stoikiy, which was patrolling in the direction of the Skagerrak Strait.

The Baltic Sea is becoming an arena for geopolitical confrontation. Russia has stepped up patrols after Sweden and Finland joined NATO in 2023-2024, changing the balance of power in the region. The Guardian reports that the Baltic states and Poland are increasing their military presence, fearing threats from Russia, especially after the Baltic Fleet exercises in April 2025.