Denmark's Aalborg airport was closed after unauthorized drones were observed in its airspace, with three smaller airports—Esbjerg, Sønderborg, and Skrydstrup—reporting similar drone activity. This incident follows a significant drone incursion at Copenhagen's Kastrup airport earlier in the week, which Prime Minister Mette Frederiksen described as a severe attack on national infrastructure. The Danish police are investigating the drones' origins and motives, with speculation about potential Russian involvement. Although officials stated there was no immediate danger to the public, they urged caution and are prepared to take down the drones if possible. The situation has heightened security concerns across Europe, particularly among NATO member states, following reports of Russian incursions into their airspace.