On October 4, 2025, Estonia’s Defence Forces Intelligence Centre released a report warning that activities of Russia’s so‑called shadow fleet in the Baltic Sea are becoming increasingly dangerous. The report stressed that restricting such operations would significantly enhance regional security. The warning follows statements by Denmark’s Defence Intelligence Service describing repeated Russian provocations in Danish straits connecting the Baltic and North Seas.
Rising Russian provocations in Danish waters
On October 3, 2025, Thomas Ahrenkiel, director of Denmark’s Defence Intelligence Service, said Russian warships had repeatedly provoked Danish forces by approaching naval vessels, aiming weapons at helicopters, and disrupting navigational systems. Some vessels operated with active sonar and jamming equipment, including at least one ship that anchored in Danish waters for over a week — a possible demonstration of Russia’s willingness to interfere if Denmark attempted to limit the shadow fleet’s movement. Denmark’s intelligence further warned of a hybrid warfare strategy by Moscow that stops short of conventional armed conflict but uses military pressure against Western states.
Strategic importance of the Baltic Sea and emerging threats
Since the full‑scale Russian invasion of Ukraine, the Baltic Sea has become a key trade route for Moscow, carrying at least 60% of Russia’s maritime oil exports. Limiting tanker traffic in the region could significantly reduce Russia’s military funding. Intelligence reports also warn of environmental risks from poorly maintained vessels and the emerging danger of Russian shadow‑fleet ships participating in security incidents, including drone flights over Denmark, the Netherlands, Sweden, Germany, and Belgium. This growing threat has prompted NATO to announce expanded patrols and enhanced monitoring capabilities in the Baltic region, including intelligence collection and surveillance platforms.
Calls for joint international action
Estonian officials have acknowledged that national capacities to counter Russia’s shadow fleet are nearly exhausted. They call for coordinated international measures, insisting coastal states have both the right and duty to inspect ships passing their waters under Article 110 of the United Nations Convention on the Law of the Sea. In summer 2024, Estonia began requiring shadow fleet vessels in the Gulf of Finland to present insurance documents as part of efforts to curb these operations.
European response and NATO engagement
On October 2, 2025, French President Emmanuel Macron announced that European states would begin preventing shadow fleet ships from entering their waters, citing that between 800 and 1,000 tankers support Russia’s war efforts. The announcement followed the arrest of two crew members of the tanker Boracay, which had departed from the Russian port of Primorsk and appeared near Denmark shortly before unidentified drones were detected near Danish strategic facilities. In late September, NATO agreed to strengthen Baltic Sea patrols in response to repeated drone incidents near critical infrastructure in the region. The alliance has committed to expanded surveillance and intelligence efforts to counteract the growing hybrid threat.
Estonia and Denmark’s warnings highlight the escalating maritime dimension of Russia’s hybrid warfare strategy, underscoring both the security and environmental stakes for the Baltic region. Coordinated action by NATO and coastal states could become a decisive factor in reducing risks and safeguarding maritime security.