Drones on NATO’s Northern Flank
By Tom Hayward | 2 November 2025
Disclaimer: This intelligence brief was originally published in early September. It has been republished to reflect updates to the document layout only.
Map of Drones Sighted in Northern Europe in September 2025
Summary
A series of drone sightings near multiple civilian airports and key military bases across Denmark and Norway between 22 and 27 September 2025 forced temporary airspace closures.
The incidents, described by Danish Defence Minister Troels Lund Poulsen as a "hybrid attack" and a part of a "systematic operation ", exposed vulnerabilities in NATO’s ability to counter low-cost, locally launched unmanned aerial systems.
NATO is highly likely to accelerate the deployment of Counter-UAS (C-UAS) technology in the medium-term, while also bolstering air defences on its northern flank. This will likely be an expansion of the recently launched Operation Eastern Sentry.
Context
On 22 September 2025, Copenhagen Airport in Denmark was forced to halt operations for nearly four hours after multiple large drones were spotted in its airspace. Oslo Gardermoen airport in Norway also temporarily closed its airspace following a separate sighting. In the following days, additional incidents involving drone sightings were reported at Aalborg, Esbjerg and Sønderborg Airports in Denmark and Air Base Skrydstrup, where Danish F-16 and F-35 jets are based. On 27 September, drones were again observed near military facilities, including Air Base Ørland in Norway and Air Base Karup, Denmark’s largest air base.
Danish police suggested that the incident in Copenhagen was conducted by “an actor who has the capabilities, the will and the tools to show off in this way”. Although noting there was no immediate evidence linking the activity to Russia, Prime Minister Mette Frederiksen stressed that Russia remains the primary security threat to Europe. The Russian Embassy in Copenhagen has denied “absurd speculations” of what it described as "staged provocations". According to Poulsen, the drones had been launched locally, either from land or a vessel at sea. Danish Justice Minister Peter Hummelgaard suggested that the core intent behind the incidents was psychological, aiming "to create fear, create division and frighten us."
Implication and Analysis
The incidents expose NATO’s inadequate ability to deal with low-cost, expendable unmanned aerial systems (UAS) threats targeting critical infrastructure. The decision by police and military personnel not to engage the drones near Copenhagen was to avoid the risk of collateral damage over populated areas. However, it also demonstrates that NATO member states cannot safely deal with drone threats within their airspace, a capability gap which adversaries can capitalise on. While NATO has used kinetic force along its eastern border, it is currently unfeasible to do so in densely populated urban areas. The deployment of high-value NATO aircraft, such as F-16s or F-35s, used in the Eastern Sentry mission, is a disproportionate, expensive and tactically ineffective response against locally launched, low-cost UAS.
Denmark declined to invoke NATO’s Article 4, which triggers consultations if a member feels threatened, unlike in the case of Poland and Estonia. This reflects a caution among many NATO states regarding the potential for escalation with Russia. This hesitancy is what hybrid warfare campaigns, such as Russia's against NATO, are designed to probe and exacerbate. In June 2025, Bruno Kahl, the outgoing head of Germany’s Federal Intelligence Service (BND) suggested that Russia was seeking to test NATO’s mutual assistance pact: “There are people in Moscow who don’t believe that NATO’s Article 5 still works.”
The incidents appear to bear some similarity to Ukraine’s ‘Operation Spider’s Web’, in which 117 attack drones were launched from lorries near major Russian air bases, destroying or damaging over 40 Russian aircraft. That incident demonstrated Ukraine’s ability to surpass Russian air defence systems by launching drone attacks locally. Similarly, the drone incidents in Denmark and Norway show how an adversary could attack critical military infrastructure deep in NATO territory, despite efforts to bolster air defences on its eastern and northern flanks.
President Of Ukraine/Wikimedia Commons, CC0 1.0
Forecast
Short-term (Now - 3 months)
NATO will likely expand Operations Baltic and Eastern Sentry, which seek to protect critical infrastructure in the Baltic Sea, with ISR platforms and air defence systems.
Russia is highly likely to continue provocations, including drone incursions, on NATO’s eastern and northern borders to probe air defences and test the alliance’s collective resolve.
Medium-term (3-12 months)
NATO will highly likely accelerate the procurement and deployment of counter-UAS systems, such as jammers, to improve air defence capabilities at military and critical infrastructure sites.
The EU will likely formalise proposals to build a “drone wall” to interlink drone defences across Europe in light of the incidents in Denmark and Norway.
