Last night we experienced the most severe attack on Danish critical infrastructure to date, said Danish Prime Minister Mette Frederiksen, after a series of large drones caused Copenhagen Airport, Scandinavia’s busiest airport, to close for several hours. The episode, which left or diverted flights from serving up to 20,000 passengers, further fueled NATO’s worries regarding an escalating trend of Russian aggression within European air space.
The drones, two or three, were characterized by Copenhagen Police Inspector Jens Jespersen as “large” and controlled by “a competent actor” possessing the “ability, the will and the means to make their presence felt.” They flew in a complicated manner, with lights switching on and off, implying intentional movement and potentially practice of operational procedure. Jespersen observed they came in from “quite a long distance away,” perhaps even remotely controlled from a ship offshore, a modus operandi in keeping with hybrid warfare tactics that exploit mobility and denial.
Authorities chose not to take them down, out of concern for proximity of civilian passenger traffic, fuel supplies, and crowded urban infrastructure. It is a reflection of the inherent difficulty in defending against unmanned aerial vehicles in civilian air space. Sizeable drones that can cause airport disruption tend to have sophisticated GPS navigation, extended communication ranges, and stamina for multi-hour flight. The payload they can carry may accommodate surveillance gear or electronic warfare packages, like GPS jammers, that have previously been employed in Baltic Sea aviation incidents.
The Copenhagen attack is echoed in a concurrent attack on Oslo Airport, where sighting of the drones caused runways to be closed and 14 flights were diverted. Norway’s intelligence agency PST is probing potential connections between the incidents. The Norwegian government has already reported three Russian airspace incursions during 2025, a decade since none were reported. The same trends have been seen in Poland, Estonia, and Romania, where Russian fighter aircraft and drones have violated NATO borders, provoking Article 4 consultations a process where allies discuss threats prior to invoking Article 5’s mutual defense provision.
NATO officials have cautioned that such incursions are a component of an “escalatory” tactic to test alliance reactions. Under the alliance’s rapid response alert systems, fighter aircraft such as Italian F-35s in Estonia are scrambled to intercept mystery aircraft, while combined radar and satellite sensor systems input into the NATO Air Command’s Recognized Air Picture. But drones pose a more difficult challenge: their low-radar cross-section and low-altitude flight profiles can outrun traditional air defense radars, necessitating specialized anti-UAS assets such as RF detection arrays, electro-optical tracking, and high-energy laser interceptors.
The larger context is Russia’s campaign of hybrid warfare, which is revealed in a CSIS database reporting attacks on transportation, government, and critical infrastructure targets tripled from 2023 to 2024. The operations tend to utilize deniable assets commercial ships, proxy agents, or locally recruited operatives to perpetrate sabotage, electronic attacks, and surveillance. At sea, Russia’s so-called “shadow fleet” has been accused of dragging anchors to cut undersea fiber-optic cables, a strategy that could be replicated to deploy or recover drones close to sensitive coastal installations.
The selection of an airport as a target highlights the vulnerability of aviation infrastructure to unmanned breaches. Airports depend on accurate navigation signals, secure communications, and reliable traffic patterns; unarmed drones can wreak havoc with these systems, triggering expensive diversions and undermining public trust. In hybrid warfare doctrine, such interference is used to “stress out and see how we react,” as Denmark’s intelligence operations chief Flemming Drejer explained, putting both technical defenses and political will to the test.
European Commission President Ursula von der Leyen characterized the incidents as a “pattern of persistent contestation at our borders,” vowing that “Europe will respond to this threat with strength & determination.” NATO surveillance and intercept capabilities are strong, but incidents in Copenhagen expose the necessity for increased integration of counter-drone capabilities into civilian airspace control, possibly through radar enhancement, AI-driven threat classification, and swift deployment of non-kinetic neutralization techniques.
Regardless of whether Russia is ultimately found to be responsible, the use pattern of the Copenhagen drones belongs in a range of actions that couple technological sophistication with strategic ambiguity. For security analysts and defense planners, the incident is less a one-time disruption than a live test of how unmanned systems can be used in the changing competition between NATO and reviving Russia.
