Russia likely used so-called shadow fleet ships as launch platforms for drones that repeatedly flew over European nations, disrupting air travel and gathering intelligence on NATO military installations, according to a new report from the International Institute of Strategic Studies think tank published Thursday.
The report, which was shared with The Associated Press ahead of its release, tracked 144 suspected drone sightings across Europe — including over NATO member nations Germany, France, Belgium, the Netherlands, the United Kingdom, and Denmark — spanning 2024 through 2026.
The frequency of those sightings peaked in late 2025, forcing temporary closures at several European airports, including facilities in Germany, Spain, and Denmark.
Danish Prime Minister Mette Frederiksen called the events in her country the “most serious attack on Danish critical infrastructure to date.”
According to the IISS, Russia deliberately kept the campaign below the level that would trigger a formal NATO collective response. The think tank called the situation a “strategic failure” for Europe, saying the continent’s air defenses are simply not equipped to handle this type of threat.
Air Chief Marshal John Stringer, NATO’s deputy supreme allied commander in Europe, told AP that each alliance member nation bears the responsibility of deciding how to handle such threats — and that many are now treating them with increasing urgency.
While several senior European officials acknowledged the difficulty of directly attributing the drone activity to Russia, Stringer stopped short of blaming Moscow. However, he noted that the behavior fits a broader pattern of disruption across Europe that Western officials have attributed to Russia since its 2022 invasion of Ukraine.
Among the countries that have confirmed drone sightings, only Sweden has publicly pointed the finger at Moscow — in a case where a military drone flew toward a French aircraft carrier from a Russian spy ship.
Russian President Vladimir Putin stated in May that Russia is not conducting a sabotage campaign against Europe.
Drones present a unique detection challenge because they travel at low altitudes and slow speeds, often appearing on radar as birds or small aircraft. They can be launched from within or near a country’s borders, making traditional missile defense systems — built to intercept high-speed projectiles fired from far away — largely ineffective. Additionally, even when a drone is brought down, tracing its origin and identifying who deployed it remains extremely difficult.
The IISS concluded that European nations must rapidly upgrade their drone defense capabilities in response to the growing number of incursions.
Lt. Gen. Jonny Lindfors, Sweden’s military representative to NATO, told AP that building a full picture of drone threats is complicated by the fact that responsibility for addressing them is divided among multiple agencies and authorities. He also described the decision to shoot down a drone as a “tough decision” given the potential for civilian casualties.
A June report from Denmark’s Defense Command acknowledged that the country’s armed forces “could have been in a stronger position” to respond to drone sightings and identified weaknesses in detection equipment. Denmark and several other European nations have since pledged to strengthen their drone defenses.
Stringer noted that countries that may have taken a “benign” view of drone threats just a few years ago now recognize that counter-drone systems are an essential component of air defense.
The IISS analyzed the movements of Russian shadow fleet vessels — ships with unclear ownership used to help Russia evade international sanctions — and determined it is highly likely these ships are being used to deploy drones.
The report concentrated on drone activity across central and northwestern Europe and did not cover incursions along NATO’s eastern flank, where both Russian and Ukrainian attack drones have crossed into European airspace.
The IISS noted that on December 2, a shadow ship called the Vezhen — previously linked to the cutting of a Baltic undersea cable — was sailing in circles off the coast of Ireland at the same time Ukrainian President Volodymyr Zelenskyy arrived for his first official visit to the country. A second vessel was reportedly nearby with its tracking signal switched off.
During that same period, four large military drones were observed off the Dublin coastline, circling above an Irish navy vessel for roughly two hours. The Irish Defense Forces did not respond to a request for comment.
The report highlighted several additional incidents tied to the presence of shadow fleet ships, many of them in Denmark:
On January 3, 2025, as the shadow fleet vessel Arctica traveled along the Danish coast, up to 20 drones were observed flying over the port of Koege before heading back out to sea.
On September 22, drone activity led to the closure of Copenhagen Airport. The IISS identified several shadow ships in the surrounding waters at the time, including the Arctica and the Boracay.
Over the following days, as the Boracay navigated around Denmark and other vessels were in the vicinity, additional drones were reported throughout the country, including near military sites.
The IISS said suspicion for at least some of the September sightings centered on the Boracay. French military personnel boarded the vessel at the end of that month, and French President Emmanuel Macron said he could not rule out the ship’s involvement in the drone flights over Denmark.
Denmark’s Defense Command confirmed that drones were detected in Danish airspace during September and October 2025. While it stopped short of linking them directly to Russia, it noted that Moscow is conducting hybrid attacks against the West on a “character and scope far beyond what Russia carried out before the war in Ukraine.”
Lindfors called it “a reasonable assumption” that Russia is using shadow ships to launch drones, though he acknowledged it is often “almost impossible” to conclusively attribute them to any single country or actor.
The IISS report also concluded that Russia likely attempted to gather intelligence on military installations in the U.K., the Netherlands, Belgium, France, and Germany, while also forcing NATO nations to activate air defenses — potentially exposing radar positions and gaps in coverage. Notable incidents cited in the report include:
The U.S. Air Force in Europe reported multiple drone sightings in November 2024 over four American air bases in the United Kingdom.
German authorities logged more than 1,000 suspicious drone sightings in 2025, including over defense manufacturers and military bases where Ukrainian soldiers were receiving training.
Defense officials in the Netherlands and Belgium reported drones spotted over military installations in November and December 2025. The IISS noted those bases are believed to store American B61 nuclear weapons.
Drone sightings were also reported at the Ile Longue submarine base in France, home to the country’s nuclear-armed ballistic missile submarines.
The U.S. Air Force in Europe declined to provide additional details on the incidents in the U.K., Netherlands, and Belgium, and would not confirm the presence of American nuclear weapons at those sites.
A British defense official, speaking anonymously due to the sensitivity of the subject, said a defense police investigation found no conclusive evidence linking the U.K. drone sightings to Russia. The Dutch Defense Ministry confirmed that drones were observed over Volkel Air Base and said it took protective measures at military sites.
The French army’s chief of staff headquarters said an investigation into the drones spotted over Ile Longue remains ongoing and did not address questions about whether shadow fleet ships may have been involved.
Requests for comment were also submitted to defense ministries in Belgium, Denmark, and Germany.
With the sheer volume of incidents mounting, Lindfors said “it would be naive to believe it’s just a coincidence” — suggesting that drone threats of this kind have become the new normal for European security.
