Unidentified drones forced the temporary closure of Denmark’s Copenhagen Airport and Norway’s Oslo Airport on Monday evening, disrupting operations for hours and stranding tens of thousands of passengers.

Copenhagen Airport halted all takeoffs and landings for nearly four hours, while Oslo Airport shut down its airspace for approximately three hours. Danish Prime Minister Mette Frederiksen condemned the incidents as an attempt to “disrupt and create unrest,” calling them the “most serious attack on Danish critical infrastructure to date.” She warned that the events aligned with recent patterns of drone intrusions, airspace violations, and cyberattacks targeting European airports.

Footage shared on social media showed large, unidentified drones causing chaos across the Nordic region, leading to over 50 flight diversions. Frederiksen cited recent suspected Russian drone incursions into Polish and Romanian airspace, as well as reports of Russian fighter jets entering Estonian airspace. However, Danish officials emphasized there was no immediate evidence linking the Denmark-Norway incidents to other cases.

Ukrainian President Volodymyr Zelenskiy alleged “Russia’s violation” of NATO airspace in Copenhagen on September 22 but provided no source for his claim. Danish police stated they found no direct connection between the drone activities in Norway and Denmark. A Copenhagen Airport spokesperson confirmed the closure began around 20:30 local time, with flights redirected to other airports.

No official attribution has been made by EU or NATO leaders, leaving the origin of the drones unclear.