The Head of the Danish Security Intelligence Service said that they did not have information to name a specific actor but the drone resembled a model of hybrid warfare seen elsewhere in Europe.

Finn Borch was speaking in a joint press conference with the National Police Commissioner, Thorkild Fogde, the Chief of Defence, Michael Wiggers Hyldgaard, and the Head of the Danish Defence Intelligence Service, Thomas Ahrenkiel, to address the drones that flew over four Danish airports overnight Wednesday into Thursday.

Borch did warn though of the the risk of Russian espionage.

"We assess the risk of Russian espionage in Denmark to be high, and we also assess the risk of Russian sabotage in Denmark to be high." he said.

Borch said that the investment into increasing Denmark's own capacity of developing drones is important and is going to be "unbelievably fast" after this incident and that cooperation with Ukraine in this regard is very important.

Drone sightings began shortly before 10 p.m. Wednesday and ended just before 1 a.m. Thursday.

Flights were halted for several hours at Aalborg Airport in northern Denmark, which also serves as a military base.

The drones appeared to be flying around the airports with their lights turned on but authorities decided against attempting to shoot down the drones, police said.

The latest drone activity came just days after a similar incident at Copenhagen Airport, conducted by what police call a “capable actor.”

While it wasn’t immediately clear who was behind the flyover, Denmark’s prime minister and NATO’s secretary-general said that Russian involvement couldn’t be ruled out.

Russia’s Embassy in Denmark on Thursday rejected claims of Russia’s involvement in the drone incidents.