In a series of unsettling incidents that have gripped Denmark and reverberated across Europe, unidentified drones have repeatedly violated Danish airspace, triggering airport closures, national security warnings, and growing speculation over potential foreign interference. The most recent episode unfolded on the night of September 24, 2025, when the airspace above Aalborg Airport—one of Denmark’s largest and a key military hub—was abruptly shut down after multiple drones were spotted flying overhead. This marked the second time in just three days that a major Danish airport faced such disruption, following a dramatic shutdown at Copenhagen Airport on September 22.
The Danish Air Transport Wing, responsible for managing military and civilian air traffic, announced the Aalborg closure to “ensure the safe handling of air traffic,” working closely with police to address the situation. Authorities have not yet disclosed the type or number of drones involved, nor have they identified the operators behind these incursions. North Jutland chief police inspector Jesper Bojgaard Madsen, speaking about the Aalborg incident, explained, “It was not possible to take down the drones, which flew over a very large area over a couple of hours. At this time, we have not apprehended the drone operators either.”
But Aalborg was not alone. According to police reports cited by France 24, drones were also sighted over Esbjerg, Sønderborg, and Skrydstrup airports late Wednesday and into Thursday morning. While only Aalborg was closed—since the other airports had no scheduled flights at the time—the pattern was clear: these were not isolated events, but rather part of what Danish authorities have characterized as a "systematic and hybrid operation by a professional actor." The drones, observed flying with lights, traversed large areas and left on their own before authorities could intervene.
Prime Minister Mette Frederiksen did not mince words in describing the gravity of the situation. After the Copenhagen Airport shutdown, she declared, “the most serious attack on Danish critical infrastructure to date.” She pointed to the deliberate and coordinated nature of the drone flights, warning that Russian involvement could not be ruled out, even though, as of now, no direct evidence has been presented. “I cannot rule out that it is Russia,” Frederiksen said, referencing a broader pattern of drone incursions and cyberattacks across Europe. “We have seen drones over Poland that should not have been there. We have seen activity in Romania. We have seen violations of Estonian airspace.”
These incidents have not occurred in a vacuum. Minutes after the Copenhagen disruption on September 22, similar drone sightings were reported over parts of Norway and Sweden, including near Oslo Airport, where Norwegian police confirmed a drone sighting forced air traffic onto a single runway for safety reasons. The Scandinavian region, already on heightened alert due to the war in Ukraine and a series of Russian aerial incursions, has found itself on the frontline of what Danish Defense Minister Troels Lund Poulsen described as a “hybrid attack.” At a press conference, Poulsen stated, “There can be no doubt that everything points to this being the work of a professional actor when we are talking about such a systematic operation in so many locations at virtually the same time. This is what I would define as a hybrid attack using different types of drones.”
In response to the growing threat, Denmark is now considering invoking NATO’s Article 4, which allows member states to request consultations with their allies if they perceive a threat to their security. “It is quite obvious that something must be done in a NATO context, also in relation to capabilities,” Poulsen said, emphasizing the need for a coordinated response. Article 4 does not automatically trigger a military response, but it does bring the issue to the forefront of the alliance’s agenda. Poland and Estonia have both invoked Article 4 in recent years following Russian airspace violations, and Denmark’s move would signal a significant escalation in its response to the drone incursions.
The impact on civilian life and commerce has been substantial. During the Copenhagen Airport shutdown, at least 50 flights were canceled and more than 50 others diverted to airports in Denmark and southern Sweden, according to Eurocontrol. The flight-tracking site Flightradar24 reported that at least 35 planes bound for Copenhagen had to change course, causing widespread disruption for travelers and airlines alike. The closures also affected Denmark’s armed forces, as both Copenhagen and Aalborg airports serve dual civilian-military functions. Aalborg Air Station, adjacent to the closed airport, is home to Denmark’s C-130 Hercules and CL-604 Challenger transport aircraft, while Skrydstrup Air Base, another site of drone activity, houses F-16 fighter jets.
The drone operators remain unidentified, and the motive behind the incursions is still unclear. Danish intelligence services, working with the police and armed forces, have launched a broad investigation. Flemming Drejer, director of operations at Denmark’s intelligence service PET, offered a sobering assessment: “Someone may not necessarily want to attack us, but rather stress us out and see how we react.” PET has described the current situation as a “high threat of sabotage.”
International reactions have been swift. NATO, while cautioning that it is “too early to say” whether Russia is responsible, warned Moscow against an “escalatory” pattern of airspace violations along the alliance’s eastern flank. Ukrainian President Volodymyr Zelenskyy condemned the drone violations of Danish airspace, linking them to a broader campaign of Russian pressure against European nations supporting Ukraine. Kremlin spokesperson Dmitry Peskov, for his part, dismissed allegations of Russian involvement as “unfounded.”
These drone incidents come amid a wider context of heightened tensions and hybrid warfare tactics in Europe. Russian airspace violations, cyberattacks targeting airports, and the use of drones for surveillance or disruption have become increasingly common, challenging NATO’s protocols for interception and collective defense. The alliance’s Eastern Sentry operation, launched after a Russian drone incursion in Poland, reflects a growing recognition that the threat landscape is evolving rapidly.
As Denmark weighs its next steps, including the possible invocation of NATO Article 4, the country finds itself at the center of a high-stakes test of European resilience and solidarity. The repeated drone incursions have exposed vulnerabilities in critical infrastructure and underscored the need for coordinated action—not just within Denmark, but across the NATO alliance. For now, the skies above Denmark remain under close watch, and the search for answers continues.