Authorities in Denmark are investigating a series of drone sightings that disrupted operations at four airports this week, raising fresh concerns about aviation security and critical infrastructure protection.
The most severe disruption occurred at Aalborg Airport on Wednesday, when drones were detected flying in restricted airspace. As a result, the airport, one of Denmark’s largest after Copenhagen, was forced to shut down for several hours.
Flights operated by Scandinavian Airlines (SAS), Norwegian, and KLM were suspended until early Thursday morning. Police said the drones traversed a wide area, making interception impossible.
Their operators remain unidentified. Investigations are ongoing in collaboration with Denmark’s intelligence service (PET) and the Armed Forces.
Additional drone sightings were reported at Esbjerg Airport, Sønderborg Airport, and Skrydstrup Air Base. While Esbjerg and Sønderborg remained open—due to no scheduled flights at the time—authorities confirmed visual sightings of drones flying with lights. The purpose and type of the drones are yet to be established.
The incidents follow a major disruption at Copenhagen Airport earlier this month, when drone activity forced the cancellation of around 100 flights, affecting tens of thousands of passengers. That shutdown prompted Prime Minister Mette Frederiksen to call it the “most serious attack on Danish critical infrastructure” to date.
Copenhagen Airport has since resumed normal operations, but officials warned that repeat incidents highlight vulnerabilities in Denmark’s airspace. PET officials have not ruled out potential links to foreign interference, though no suspects have been named.
European Commission President Ursula von der Leyen commented on the incidents, saying they reflect a “broader pattern of security challenges at Europe’s borders and infrastructure.” She emphasized the need for collective responses to unmanned aerial threats.
Meanwhile, Aalborg Airport, which serves as a key hub for northern Denmark, saw all flights grounded until Thursday morning. While less busy than Copenhagen, the closure disrupted travel across domestic and international routes.
The incidents also coincide with regional concerns. On Monday evening, Oslo Airport in Norway briefly suspended operations after a drone was sighted nearby. Authorities in both Denmark and Norway say they are sharing intelligence and coordinating security responses.
Aviation experts warn that drone incursions near airports pose significant risks, particularly to passenger aircraft during takeoff and landing. “The technology to detect and neutralize drones exists, but deploying it across all airports is a complex and costly challenge,” said one aviation security analyst.
For now, Danish authorities are increasing monitoring around airports and military installations. Police have urged the public to report drone sightings and have cautioned operators that flying drones near airports is strictly prohibited under Danish law.
As investigations continue, the incidents underline how drones, whether operated recklessly or deliberately, have become a growing security challenge across Europe’s skies. Denmark, like other countries, is now weighing tougher measures to secure its critical air infrastructure against future disruptions.