Denmark · European wave.“Drones” over Europe · airports shut and bases overflown

Between September 22 and December 4, 2025, a sequence of unidentified aerial incursions swept through some ten NATO countries, closing civilian airports and overflying military and nuclear installations. Ten days earlier, on September 12, after Poland invoked Article 4 over an incursion by Russian drones, NATO had launched Operation Eastern Sentry to reinforce surveillance of the eastern flank. The sequence began on the night of September 22: Copenhagen Airport suspended operations for close to four hours after "two or three large drones" were sighted inside its controlled airspace, and Oslo-Gardermoen closed briefly the same night. Copenhagen's police chief, Jens Jespersen, described sophisticated flight patterns and suggested the control site might be "on a ship". Danish Prime Minister Mette Frederiksen called it the most serious attack the country's critical infrastructure had suffered to date.

The pattern repeated for eleven weeks. In Denmark, Aalborg and Billund closed and there were sightings beside the Skrydstrup and Karup bases. In Germany, an internal Schleswig-Holstein government memo documented drone formations, some with a "mother drone" (a larger object accompanied by smaller craft), over ThyssenKrupp's marine division, Kiel's university hospital, the Kiel Fjord, power stations and the regional parliament; the state interior minister cited eight-meter wingspans, and the federal government counted 172 drone-related air traffic disruptions in 2025 alone. Munich closed twice within twenty-four hours in early October, Berlin Brandenburg and Bremen in the following weeks. In Norway there were sightings over Ørland air station, and police in Brønnøysund filmed five to six possible drones simultaneously in restricted airspace.

Belgium concentrated the most delicate phase. On November 2 several craft were observed over Kleine Brogel (the base that, according to repeated press reports, stores U.S. tactical nuclear weapons), a helicopter was scrambled and the objects moved off toward the Netherlands; the same day there were overflights at Leopoldsburg and Marche-en-Famenne. On November 9 Liège Airport closed and three drones were seen over the Doel nuclear power station; the United Kingdom, France and Germany announced support with personnel and equipment. On November 22 Dutch military personnel opened fire on craft over Volkel air base, a nuclear weapons storage site, and no wreckage was recovered. On December 4 five unidentified drones overflew Île Longue, the operating base of France's ballistic-missile submarines; a jammer was used, none was brought down and no operators were identified.

On June 25, 2026, nine months later, Danish police closed the Copenhagen investigation with no suspects. Chief Inspector Søren Thomassen summed up the result this way: "We cannot confirm that there has been drone activity in and around the airport. At the same time, we cannot rule out the possibility that there has been drone activity." Investigators had reviewed witness statements, photographs, videos, CCTV footage, radar data and extensive air and maritime traffic records. Their conclusion was that there had been unexplained activity in the airspace that night, but that nothing they had gathered demonstrated the objects were drones.

At the press conference, inspector Mads Helios said 87 witnesses had been interviewed, that there were three objects in the air and that commercial traffic had in some cases been mistaken for drones; Thomassen added that what the airport's bird radar recorded was, in most cases, birds and insects, and that some radar returns indicated objects the police cannot identify with certainty. According to the newspaper Information, the radar data showed unknown objects crossing the Øresund toward Saltholm at over 100 km/h.

The Danish national police reported the same day that most of the more than 7,000 reports of possible drones received across the country since September 22 had been quickly cleared up as, for example, airliners or wind-turbine blades, and that in some investigations, among them those of the Copenhagen and North Jutland police, it could be neither confirmed nor ruled out that there were drones. According to TV 2, the Danish Armed Forces had concluded the previous week that there were indeed drones over Denmark in the autumn in connection with the EU summit held in Copenhagen; the broadcaster does not say how many or who operated them.

In eleven weeks and ten countries not a single craft was recovered, identified or confirmably brought down, despite the fire opened at Volkel and the jammer used at Île Longue. The dominant attribution, to Russia and a hybrid-warfare campaign, rests on context (there is a war under way, Poland invoked Article 4, NATO deployed Eastern Sentry), but it was never proven: it is an inference from circumstances, with not one craft identified.

Danish police spent nine months trying to establish the conventional explanation (that what was seen were drones), cross-checking testimony, photographs, video, CCTV, radar and air and maritime traffic records, and could neither demonstrate nor rule it out: the investigators started from something known, drones, and could not confirm it. The closure of a national airport that the prime minister had called an attack on critical infrastructure thus ended with no proof that drones had been there.

The Danish national police attributed most of the public's reports to conventional causes, but left the Copenhagen and North Jutland investigations unresolved, and the Danish Armed Forces maintain that there were drones around the EU summit. Nothing in the sequence points to anything non-human.