A night of drone incidents at airports and military bases across the Jutland region in western Denmark has left no damage, although it has shown the vulnerabilities of the European country's defenses.

In an age of hybrid warfare, there is a sense of shame in Denmark, one of the founding members of NATO, because its critical infrastructure has become so vulnerable.

Aalborg and Billund airports had to close, and drones were spotted in Esbjerg, Sonderborg, and Skrydstrup. Aalborg also functions as a military base, and Skrydstrup is home to some of the Danish Air Force's F-35 and F-16 fighter jets. Drones were also seen over the Jutland Dragon Regiment in Holstebro.

Since then, there have been reports that police are investigating drone activity around Denmark's oil and gas platforms in the North Sea and near the central port of Korsor.

The question now facing the country's military is how to respond.

Hybrid warfare

None of the drones have been shot down; Defense chiefs decided it was safer not to, but that's not a long-term solution.

Of course, Denmark is not alone.

Norway, Estonia, Poland, Bulgaria, and Romania have all been targeted by hybrid warfare in recent weeks. All are on NATO's eastern flank.

Both Estonia and Poland invoked NATO's Article 4 this month after Russian warplanes entered Estonian airspace for 12 minutes, and around 20 Russian drones violated Polish airspace and were shot down.

Denmark has said a “professional actor” was responsible for the drone attacks it recorded, and has not given further details.

Article 4 brings the defense alliance together for consultations when a member's “territorial integrity, political independence, or security” is threatened.

The Danish government is currently evaluating whether to invoke it as well.

This is a serious moment for Denmark, and its top officials quickly called a press conference,where Defense Minister Troels Lund Poulsen said the drone action appeared “systematic” given the number of locations attacked.

“This is what I would define as a hybrid attack,” he said, declining to assign blame, as they have no concrete evidence.

Russia has not been ruled out, something Prime Minister Mette Frederiksen made clear after the drones appeared Monday night over Copenhagen.

Moscow “firmly rejects” any involvement, and its embassy in Copenhagen has denounced the incidents as a “staged provocation.”

Russia “a threat”

However, Frederiksen is in no doubt about the risk and said last week that Russia “will be a threat to Europe and Denmark for years to come.”

No one has been hurt yet, mainly because the drones were allowed to continue their flight course.

Defense chief Michael Hyldgaard put it simply: “When you shoot something down in the air, something else also comes back down.”

One example of this was when the roof of a house was destroyed in Wyryki, eastern Poland, allegedly by a missile fired by a NATO aircraft.

Police in Jutland did say they would try to shoot down the drones if it could be done safely, and the military has made clear it is prepared to do so over military installations, depending on “the assessment of the specific threat and the possible consequences of the shootdown.”

But so far, that hasn't happened.

Kjeld Jensen, of the University of Southern Denmark's drone center, accepts that it is embarrassing that the vulnerabilities of Denmark may have been exposed, but believes the police and military acted appropriately.

“I wouldn't shoot down drones if they are over an urban area or an airport,” he says, “as they have to come down, and there could be fuel or batteries creating a fire, which is also a risk to consider.”

“You have to decide whether it's more dangerous than letting it fly,” says Peter Viggo Jakobsen of the Royal Danish Defense Academy. “But it's not a sustainable situation and we need to find ideas.”

Denmark's cautious approach is markedly different from Poland's since Russia's drone incursions there on September 10.

This week, Polish Foreign Minister Radek Sikorski warned Moscow at the UN: “If another missile or aircraft crosses our territory without permission, intentionally or accidentally, and is shot down and its remains fall on NATO territory, don't come here to complain. They have been warned.”

Without the tools

Denmark and many of its neighbors don't have the kind of tools they need to shoot down drones.

The government recently announced plans for an “integrated layered air defense,” along with an investment in long-range precision weapons to strike at territory.

But that's of little use to Denmark's defenses right now.

“From an engineering perspective, it's much easier to build a drone that can fly than to build something that can stop them from flying,” notes Jensen of the University of Southern Denmark.

On Friday, Denmark will join several NATO allies and Ukraine to discuss the idea of ??erecting a “drone wall” proposed by the enemy European Commission President Ursula von der Leyen to protect the EU's eastern borders.

What will be discussed is more likely to focus on the kind of armed drones that arrived in Polish airspace, rather than the unarmed drones with bright lights seen over Denmark.

The aim is to create an early detection system, although again, that might not have helped Denmark that night if the drones sighted over Jutland were launched locally.

If Russia was behind the drones, despite its denials, then by hybrid warfare standards this operation appears to have been a success.

Airports were briefly closed, Denmark's military sites were exposed as vulnerable, and senior ministers were forced to hold a hasty press conference to assuage public concerns.

But it has given the Danes a fresh wake-up call. Police have raised their crisis level, and the minister defense has spoken of the country facing a new reality.