ISTANBUL

Danish authorities closed airspace over multiple airports late Thursday amid reports of drone activity, prompting flight diversions and heightening security concerns over what Prime Minister Mette Frederiksen described as “a hybrid war unfolding on Danish soil.”

Airspace over Aalborg Airport in northern Denmark reopened after being shut Thursday night following reports of suspected drone activity, Danish police said.

Airports in Esbjerg, Sonderborg, Skrydstrup and Billund were also all affected, with Aalborg Airport experiencing repeated closures, news broadcaster TV2 reported.

Shortly before midnight, North Jutland Police confirmed shutting down airspace again after one of their officers reported a drone sighting.

“So far, two flights bound for Aalborg have been diverted,” police said, noting that additional officers had been deployed to the area.

Frederiksen addressed the nation in a taped video statement, warning that the incidents highlighted Denmark’s vulnerabilities.

“Drones have been seen several times near critical infrastructure, both military and civilian. These are hybrid attacks designed to create insecurity and division. We must expect more,” she said.

She said that no European country can defend itself against such threats alone, stressing the importance of cooperation among NATO member states and the buildup of Europe’s defense industry.

“Even Ukraine, after more than three years of fighting, cannot defend itself alone against Russia,” Frederiksen said.

NATO Secretary General Mark Rutte said the alliance was taking the situation “very seriously.”

French President Emmanuel Macron also expressed “full solidarity with Denmark” and offered support in protecting Danish airspace.

Danish intelligence officials acknowledged gaps in current capabilities to counter drones.

“It is an incredibly complicated task, not something solved with just a rifle or a jammer,” said the head of the Danish Armed Forces Intelligence Service, Thomas Ahrenkiel.

Copenhagen Police reported receiving hundreds of calls from residents claiming to have seen drones. Authorities urged the public to document suspected drone activity on video and share it with investigators.

While officials have not identified those behind the incidents, Frederiksen pointed to Russia as the primary threat.

“We see similar hybrid episodes across Europe. We must look at the pattern, and it does not look good,” she warned.

“We are not at war in the traditional sense, but a hybrid war has begun,” she said, adding that authorities had raised preparedness levels and deployed anti-drone capacity around critical infrastructure.