On the night of September 22, 2025, Copenhagen’s bustling Kastrup airport—a vital hub for northern Europe—fell eerily silent. Flights were grounded, passengers stranded, and the usual rhythm of takeoffs and landings abruptly halted. The culprit? Not a technical glitch, nor a weather anomaly, but a series of mysterious drones that swooped in from multiple directions, forcing authorities to shut down all air traffic for nearly four hours. As Danish Prime Minister Mette Frederiksen bluntly put it, this was “the most serious attack on Danish infrastructure so far,” according to BBC reporting.
It’s not often that a few unmanned aerial vehicles can paralyze a major international airport and leave 20,000 travelers in limbo. Yet, as videos circulated by local media revealed, these were not your average hobbyist drones. Described by police and eyewitnesses as "relatively large unidentified craft with green lights," the drones appeared to be operated by someone with considerable skill—capable of maximizing nuisance and causing alarm, as noted by The Guardian. They didn’t just hover aimlessly. Instead, they approached the airport from different directions, switched their lights on and off, and eventually vanished as suddenly as they had appeared.
The incident wasn’t isolated to Denmark. Just hours later, Oslo’s main airport in Norway also shut down for three hours after a possible drone sighting, diverting fourteen flights. Norwegian authorities, as Reuters reported, are still trying to determine whether the two events were linked, with the Norwegian Police Security Service stating the situation remains “unclear” and that they are in “routine contact with actors both nationally and internationally.”
What’s behind these brazen drone incursions? Danish authorities are not ruling anything out. “It says something about the times we live in and what we as a society must be prepared to deal with,” Prime Minister Frederiksen told reporters. She linked the Copenhagen event to a “wider pattern” of suspected Russian drone intrusions and airspace violations that have rattled Europe in recent weeks. Just two weeks earlier, nineteen Russian decoy drones crossed into Polish airspace, prompting NATO to scramble jets and establish Operation Eastern Sentry—an enhanced air policing mission over eastern Europe involving the UK, France, Germany, and Denmark. Only days later, three Russian MiG-31 fighter jets entered Estonian skies, lingering for twelve minutes before being intercepted.
“We are obviously not ruling out any options in relation to who is behind it,” Frederiksen stated in a message to the media, as cited by Reuters. “And it is clear that this fits in with the developments we have observed recently with other drone attacks, violations of airspace, and hacker attacks on European airports.” She went further in comments to Denmark’s public broadcaster, DR: “I certainly cannot deny in any way that it is Russia.”
That suspicion, however, has been met with sharp denials from Moscow. Kremlin spokesman Dmitry Peskov called the allegations “unfounded,” while Russia’s ambassador to Denmark, Vladimir Barbin, suggested the incident was designed “to provoke NATO countries into a direct military confrontation with Russia,” according to Reuters. Moscow has consistently denied responsibility for any so-called hybrid attacks in Europe, which Western security agencies say now range from physical sabotage to disinformation, espionage, and cyberattacks.
On the ground in Copenhagen, police found themselves facing a perplexing threat. Chief Superintendent Jens Jespersen told reporters that the drones “came from different directions, turning their lights on and off, before eventually disappearing after several hours.” Investigators are considering several hypotheses, including the possibility that the drones were launched from ships in the busy Baltic Sea shipping lanes—a theory supported by the presence of a Royal Danish Navy ship patrolling waters near the airport the following morning. “It’s an actor who has the capabilities, the will, and the tools to show off in this way,” Jespersen explained.
The challenge for authorities was compounded by the airport’s location in a densely populated area. Shooting down the drones wasn’t a realistic option, given the risks to planes in the air and people on the ground. Jamming the drones’ frequencies was also off the table, as Bob Tollast of the Royal United Services Institute explained to The Guardian, due to the risk of disrupting civilian radio communications and cell phone networks.
The closure of Kastrup airport wasn’t just an inconvenience. It exposed a glaring vulnerability in European airspace security. “Another reminder of how vulnerable airports are,” Tollast remarked. The incident has prompted urgent questions about how to defend critical infrastructure from cheap, relatively simple, but potentially highly disruptive drone technology—especially as modern Russian drones like the $10,000 Gerberas (with a range of about 370 miles) and the $75,000 Shaheds (capable of flying over 1,000 miles) could reach Copenhagen from Russian territory or even further afield.
Denmark’s intelligence service, PET, has assessed that the motive behind the incursion was likely to “disrupt, create unrest... to see how far you can go and test the limits.” Flemming Drejer, PET’s director of operations, suggested that “someone may not necessarily want to attack us, but rather stress us out and see how we react.” The sentiment was echoed by Danish police, who described the operator as having both the “will and tools to show off... perhaps also to practice.”
Meanwhile, the impact of these incidents goes beyond the immediate chaos at airports. They come on the heels of a ransomware attack—possibly of Russian origin—that disrupted flights in Brussels, Berlin, and Heathrow since September 19, 2025, knocking out automated check-in systems and causing widespread delays. Prime Minister Frederiksen tentatively linked the drone flights to this hacking episode, underscoring the growing threat of hybrid warfare tactics that blur the line between physical and digital sabotage.
The broader context is one of escalating tension. Norway’s government reported that Russia violated its airspace three times in 2025—in April, July, and August—though it’s unclear whether these were deliberate or navigation errors. “Regardless of the cause, this is not acceptable,” Norwegian Prime Minister Jonas Gahr Store stated. Across the region, countries like Poland and Sweden have warned they will shoot down any object violating their airspace, while NATO has pledged to move troops and fighter jets eastward to bolster its defenses.
Yet, even as NATO declared on Tuesday that it would use “all necessary military and non-military tools to defend ourselves,” it’s not obvious that these measures have deterred Russia—or whoever may be behind the drone incidents. As former White House adviser Fiona Hill has pointed out, while the West does not consider itself at war with Russia, Moscow may see things differently, especially as Europe becomes Kyiv’s principal backer in the ongoing conflict in Ukraine.
For now, the skies over Copenhagen and Oslo have returned to normal, but the sense of unease lingers. The events of September 22 and 23, 2025, have left European officials, security experts, and citizens alike with a sobering question: just how secure are the continent’s most critical infrastructures in an age of cheap drones and hybrid threats?
As the dust settles, one thing is clear: the old playbook for airport security is no longer enough. Europe’s response in the coming months may well determine whether such incidents become the new normal—or a turning point in the defense of its skies.
