Denmark’s Aalborg airport was forced to close late Wednesday after several of the country’s airports reported unauthorised drone activity, prompting officials to warn of a possible hybrid attack.
Police confirmed three other smaller airports also registered drone sightings, though none were shut down. With concerns mounting over Russian efforts to test NATO’s air defences, Danish authorities described the incident as a “hybrid attack.”
The closure at Aalborg, which serves both commercial and military flights, came just days after Copenhagen airport was briefly shut due to drones. Similar incursions have been reported in Estonian, Polish, and Romanian airspace, fuelling accusations that Russia is probing NATO readiness.
US President Donald Trump on Tuesday urged NATO members to shoot down Russian aircraft violating their airspace. A day later, European Commission President Ursula von der Leyen said the possibility of downing “fighter jet[s]” intruding into NATO territory was “on the table.”
Danish police said they were investigating the source of the drones and had not ruled out a prank. Later on Thursday, officials said the scale of the operation pointed to a professional, coordinated assault.
“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,” Defence Minister Troels Lund Poulsen told reporters.
Poulsen added Denmark does not see itself under direct military threat and has yet to decide whether to invoke NATO Article 4, which would trigger consultations among alliance members. Estonia made such a request on September 19 after three Russian fighter jets entered its airspace.
Drone Activity Spreads
Police said “more than one” drone was seen near Aalborg airport, located in northern Jutland, Denmark’s fourth-largest city. The sightings mirrored those that disrupted flights at Copenhagen on Monday, when unidentified drones forced a four-hour shutdown.
The closure of Aalborg also disrupted Denmark’s armed forces, which use the site as a military base. “It is too early to say what the goal of the drones is and who is the actor behind,” a police spokesperson told Reuters, adding that drones would be taken down if possible.
Authorities said the aircraft left Aalborg airspace by Thursday morning but were later reported near Esbjerg, Sønderborg, and Skrydstrup airports. Fighter Wing Skrydstrup is home to Denmark’s F-16 and F-35 jets.
The first drones were observed at 9:44pm local time (19:44 GMT) on Wednesday and remained overhead for several hours. Eurocontrol, Europe’s air traffic body, said Aalborg arrivals and departures would remain at a “zero rate” until 04:00 GMT on Thursday.
Police said they could not identify the type of drones or confirm whether they matched those seen at Copenhagen. Officials labelled the Copenhagen incident the most serious assault yet on national infrastructure and linked it to wider suspected Russian incursions across Europe.
Norway also briefly shut Oslo airport on Monday after a drone sighting. Danish Prime Minister Mette Frederiksen said she “cannot reject in any way that it could be Russia” behind the Copenhagen incident.
Von der Leyen warned on social media that “our critical infrastructure is at risk” and vowed Europe would respond “with strength and determination.”
Speaking later to CNN, she added: “My opinion is we have to defend every square centimetre of the territory… the option of shooting down a fighter jet that is intruding our airspace is on the table.”
The Kremlin dismissed the accusations. Spokesperson Dmitry Peskov called them “unfounded,” insisting Russian “aircraft are guided by international regulations in all their flights and do not violate them in any way.”
Earlier this month, Poland closed four airports, including Warsaw, after repeated drone incursions it blamed on Russia. NATO allies have since pledged to reinforce border defences and reaffirmed their collective commitments.
