Drone incidents at airports and military bases all over Jutland, western Denmark, have not caused any harm or damage - and yet they have exposed the country's defences as vulnerable to attack.
In an era of hybrid warfare, there is a sense of embarrassment in Denmark - a founding member of the North Atlantic Treaty Organization (Nato) alliance - that its critical infrastructure has become so vulnerable.
Aalborg and Billund airports had to close on Wednesday night, while drones were spotted at Esbjerg, Sonderborg and Skrydstrup. Aalborg also serves as a military base and Skrydstrup is home to some of the air force's F-35 and F-16 war planes. Drones were also seen over the Jutland Dragoon regiment at Holstebro.
There have since been reports of police investigating drone activities around Denmark's oil and gas platforms in the North Sea, and near the central port of Korsor.
Aalborg airport briefly closed again on Thursday night following another suspected drone sighting, police and national media said on Friday.
The question now facing the country's military is how to respond.
None of the drones have been shot down - defence chiefs decided it was safer not to, but that is not a long-term solution.
Denmark is, of course, not alone. Norway, Estonia, Poland, Bulgaria and Romania have all been subjected to hybrid warfare in recent weeks. All are on Nato's eastern flank.
Denmark has said a "professional actor" was responsible for the drone attacks it saw, and left it at that.
This is a serious moment for Denmark, and its top brass - government, defence and police - quickly called a press conference where Defence Minister Troels Lund Poulsen said it looked systematic, because of the number of locations targeted.
Prime Minister Mette Frederiksen has indicated that Russia could be involved, though the Kremlin has denied any connection.
Denmark's cautious approach stands in contrast to the more aggressive stance taken by some of its neighbors, with ongoing discussions on bolstering defenses against similar threats in the future.
The situation underscores the emerging reality of heightened security concerns and the urgent need for enhanced surveillance and defense capabilities in the face of modern hybrid threats.
