Denmark’s Aalborg Airport closed on Thursday after drones entered its airspace, local police reported. The shutdown came just two days after Copenhagen Airport faced a similar disruption. Consequently, authorities are investigating possible links between the incidents.

The Danish national police said the drones showed the same patterns that had grounded flights at Copenhagen Airport for four hours earlier this week. In addition, they noted that Aalborg Airport hosts a military base, meaning the incident also affected Denmark’s armed forces.

Earlier on Tuesday, Denmark described the Copenhagen Airport incident as its most serious infrastructure attack yet. Moreover, officials linked the drone sightings to previous Russian incursions and disruptions across Europe.

Drones Spotted in Northern Jutland

Northern Jutland police confirmed that “more than one drone” appeared in Aalborg’s airspace. They added that the drones were flying with their lights on. However, a police spokesperson said, “It is too early to say what the goal of the drones is and who is the actor behind it.”

Flight Chaos at Copenhagen Airport

The Copenhagen incident caused major travel disruption. For instance, Eurocontrol reported that at least 50 flights were cancelled. In addition, more than 50 flights were diverted to airports in Denmark and southern Sweden, including Billund, Aarhus, Malmö, and Gothenburg. Furthermore, flight-tracking site Flightradar24 reported that at least 35 planes bound for Copenhagen had to change course.

Minutes after the Danish incidents, drones were reported over Norway and Sweden. Norwegian police confirmed a drone near Oslo Airport. Consequently, they forced air traffic onto a single runway “for safety reasons.”

NATO and International Reactions

NATO said it was “too early to say” if Russia caused the incidents. However, it warned Moscow to stop any “escalatory” airspace violations along its eastern flank. Similarly, Ukrainian President Volodymyr Zelenskyy condemned what he called a Russian violation of Denmark’s airspace in a message on X.

Meanwhile, Danish intelligence warned that the country faces a “high threat of sabotage.” Flemming Drejer, director of operations at Denmark’s intelligence service PET, said, “Someone may not necessarily want to attack us, but rather stress us out and see how we react.”