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Rapid communication – CBRNe implications of drone incursions in Denmark

Written by Zoe Rutherford on .

Authors: Lars Thomsen, Soiwisa Soikum and Sergii Makovetskii

Gnacode Inc. 11 Sunrise Way SW, Medicine Hat, Alberta T1B4S3, Canada

Corresponding author: Lars Thomsen email:

Recent incursions in Europe by large numbers of drones reported in Poland the 10th of September 20251, and the 3rd of January in Denmark2 and very recently in Denmark the 24th September 20253 raises the concern that such devices could be utilized to disseminate biological weapons in aerosol format4.

The 24th of September drone incursions were observed in Denmark by an unknown large number of drones of unknown origin. The incursions targeted military installations such as naval bases and air bases, and other airports.

In a simulation scenario of a biological attack, we used the approximate geolocation of 6 confirmed sites in Denmark widely published in various media as being the location of sighted drones. One report was made by citizens near Karup Airbase which hosts the Danish Air Command, this has not been confirmed by official sources but reported in the Danish news media5.

We simulated a spread of a 50 kg (110 lb) weapons grade biological agent per drone, which is the payload of the Iranian produced HESA Shahed 136 drone.  A weapons grade powder of 50 kg (110 lb) can contain 5E16 CFU of Anthrax spiked with Smallpox per drone. We chose delivery as a single point dissemination, at a height of 10 meters, and we integrated the aerosol concentration from 0 to 4 meters above ground and tracked the spread over 24 hours, by a simple dispersion algorithm developed in Python and available wind data See Note 1..  In Denmark the 24th of September the wind direction was South-East bound. The results are shown in Figure 1.

The simulation shows that 13 out of 21 military installations would be affected. The 24th of September was characterized by low wind speeds of 2.50 m/sec, which is ideal for effective high concentration dissemination in the affected areas. A biological attack would go unseen, due to lack of biological monitoring and first be reported when people in the affected areas start to report sickness. An incubation period of 5–14 days is expected due to the incubation period of the diseases. Once in effect the Danish defense in the affected areas would be partially or fully incapacitated. Hereto, all airports were affected which will cause the infections to spread rapidly to other countries by contaminated passengers, a topic that has been extensively modelled during the Covid-19 pandemic6.

Note 1: Open-source codes available at the company’s GitHub site, access can be given upon request.

  1. Charlish, A., Kelly, L. & Erling, B. Poland downs drones in its airspace, becoming first NATO member to fire during war in Ukraine. Reuters (2025).
  2. Danish police investigate mystery drone sightings – DW – 01/04/2025. dw.com https://www.dw.com/en/danish-police-investigate-mystery-drone-sightings/a-71217317.
  3. Drones disrupt Danish airports again, Russia denies involvement. Reuters (2025).
  4. Lars Thomsen, Soiwisa Soikum, & Sergii Makovetskii. Rapid communication – CBRNe implications of drone incursions in Europe. https://cbrneworld.com/news/rapid-communication-cbrne-implications-of-drone-incursions-in-europe.
  5. Lauridsen, A. L. Flere midt- og vestjyder mener at have set droner. TV MIDTVEST https://www.tvmidtvest.dk/midt-og-vestjylland/flere-midt-og-vestjyder-mener-at-have-set-droner-9f178 (2025).
  6. Kuo, P.-F. & Chiu, C.-S. Airline transportation and arrival time of international disease spread: A case study of Covid-19. PLOS ONE 16, e0256398 (2021).

 

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