Denmark on Saturday reported more mysterious drone sightings — this time over military installations, including its largest military base — after incursions at airports grounded flights this week. The NATO country is still mulling how to respond.

Denmark’s Armed Forces reported that more drones were observed overnight, according to Reuters. 

“The Danish Defense can confirm that drones were observed at several of the Danish Defense’s locations last night. Several capabilities were deployed,” a spokesperson told the outlet.

Police said drones were spotted near the Karup air base in western Denmark, Reuters reported, citing Ritzau News agency.

On Monday, a similar drone incident impacted Copenhagen Airport. Unlike the incident at Aalborg, some suspected Russia could have been the culprit behind the attack.

Danish Prime Minister Mette Frederiksen said it was “the most serious attack on Danish critical infrastructure to date,” according to reports. She added that the country was “not ruling out any options in relation to who is behind it,” Reuters reported.

NATO Secretary-General Mark Rutte said on Friday that he spoke with Frederiksen about the drones and that the alliance was taking the incidents “very seriously.” 

“NATO Allies and Denmark are working together on how we can ensure the safety and security of our critical infrastructure,” Rutte said in a post on X.

Danish Prime Minister Mette Frederiksen speaks to the media following talks with German Chancellor Olaf Scholz at the Chancellery on Jan. 28, 2025, in Berlin. (Maja Hitij/Getty Images)

While some believed the country was considering triggering NATO’s Article 4 to convene allied countries over the drone incidents, Danish Foreign Minister Lars Lokke Rasmussen said the country had “no reason to do so,” according to Reuters. Rasmussen said that after Article 4 was recently triggered due to aerial disturbances in Poland and Estonia, Denmark did not feel a need to do the same, Reuters reported.

Despite neither triggering a NATO response nor shooting down the drones, Denmark is still mulling a possible response to the sightings.