William H. Johnson, CAPT, USN/Ret, holds a Master of Aeronautical Science (MAS) from Embry-Riddle Aeronautical University, and a MA in Military History from Norwich University. He is currently an Adjunct Assistant Professor at Embry-Riddle in the College of Aeronautics, teaching unmanned system development, control, and interoperability. Divergent Options’ content does not contain information of an official nature nor does the content represent the official position of any government, any organization, or any group.

Title:  Simple Lethality: Assessing the Potential for Agricultural Unmanned Aerial and Ground Systems to Deploy Biological or Chemical Weapons

Date Originally Written:  August 15, 2020.

Date Originally Published:  November 18, 2020.

Author and / or Article Point of View:  The author is a retired U.S. Naval Flight Officer who held command of the Navy’s sole unmanned air system squadron between 2001 and 2002. He has presented technical papers on unmanned systems, published on the same in professional journals, and has taught unmanned systems since 2016. The article is written from the point of view of an American analyst considering military force vulnerability to small, improvised, unmanned aerial or ground systems, hereby collectively referred to as UxS, equipped with existing technology for agricultural chemical dispersal over a broad area.

Summary:  Small, locally built unmanned vehicles, similar to those used in agriculture, can easily be configured to release a chemical or biological payload. Wide, air-dispersed agents could be set off over a populated area with low likelihood of either interdiction or traceability. Domestic counter-UAS can not only eliminate annoying imagery collection, but also to mitigate the growing potential for an inexpensive chemical or biological weapon attack on U.S. soil.

Text:  The ongoing development and improvement of UxS – primarily aerial, but also ground-operated – to optimize efficiency in the agricultural arena are matters of pride among manufacturers.  These developments and improvements are of interest to regulatory bodies such as the Federal Aviation Administration, and offer an opportunity to those seeking to inflict easy chemical or biological operations on U.S. soil. While the latter note concerning opportunity for enemies, may appear flippant and simplistic at first blush, it is the most important one on the list. Accepting the idea that hostile entities consider environment and objective(s) when choosing physical or cyber attack platforms, the availability of chemical-dispersing unmanned vehicles with current system control options make such weapons not only feasible, but ideal[1].

Commercially available UxS, such the Yamaha RMAX[2] or the DJI Agras MG-1[3], can be launched remotely, and with a simple, available autopilot fly a pre-programmed course until fuel exhaustion. These capabilities the opportunity for an insurgent to recruit a similarly minded, hobbyist-level UAS builder to acquire necessary parts and assemble the vehicle in private. The engineering of such a small craft, even one as large as the RMAX, is quite simple, and the parts could be innocuously and anonymously acquired by anyone with a credit card. Even assembling a 25-liter dispersal tank and setting a primitive timer for release would not be complicated.

With such a simple, garage-built craft, the dispersal tank could be filled with either chemical or biological material, launched anytime from a suburban convenience store parking lot.  The craft could then execute a straight-and-level flight path over an unaware downtown area, and disperse its tank contents at a predetermined time-of-flight. This is clearly not a precision mission, but it would be quite easy to fund and execute[4].

The danger lies in the simplicity[5]. As an historical example, Nazi V-2 “buzz bomb” rockets in World War II were occasionally pointed at a target and fueled to match the rough, desired time of flight needed to cross the planned distance. The V-2 would then simply fall out of the sky once out of gas. Existing autopilots for any number of commercially available UxS are far more sophisticated than that, and easy to obtain. This attack previously described would be difficult to trace and almost impossible to predict, especially if assembly were done with simple parts from a variety of suppliers. The extrapolated problem is that without indication or warning, even presently available counter-UxS technology would have no reason to be brought to bear until after the attack. The cost, given the potential for terror and destabilization, would be negligible to an adversary. The ability to fly such missions simultaneously over a number of metropolitan areas could create devastating consequences in terms of panic.

The current mitigations to UxS are few, but somewhat challenging to an entity planning such a mission. Effective chemical or weaponized biological material is well-tracked by a variety of global organizations.  As such, movement of any amount of such into the United States would be quite difficult for even the best-resourced individuals or groups. Additionally, there are some unique parts necessary for construction of a heavier-lift rotary vehicle.  With some effort, those parts could be cataloged under processes similar to existing import-export control policies and practices.

Finally, the expansion of machine-learning-driven artificial intelligence, the ongoing improvement in battery storage, and the ubiquity of UxS hobbyists and their products, make this type of threat more and more feasible by the day. Current domestic counter-UxS technologies have been developed largely in response to safety threats posed by small UxS to manned aircraft, and also because of the potential for unapproved imagery collection and privacy violation. To those, it will soon be time to add small scale counter-Weapons of Mass Destruction to the rationale.


[1] Ash Rossiter, “Drone usage by militant groups: exploring variation in adoption,” Defense & Security Analysis, 34:2, 113-126, https://doi.org/10.1080/14751798.2018.1478183

[2] Elan Head, “FAA grants exemption to unmanned Yamaha RMX helicopter.” Verticalmag.com, online: https://www.verticalmag.com/news/faagrantsexemptiontounmannedyamaharmaxhelicopter Accessed: August 15, 2020

[3] One example of this vehicle is available online at https://ledrones.org/product/dji-agras-mg-1-octocopter-argriculture-drone-ready-to-fly-bundle Accessed: August 15, 2020

[4] ”FBI: Man plotted to fly drone-like toy planes with bombs into school. (2014).” CBS News. Retrieved from
https://www.cbsnews.com/news/fbi-man-in-connecticut-plotted-to-fly-drone-like-toy-planes-with-bombs-into-school Accessed: August 10, 2020

[5] Wallace, R. J., & Loffi, J. M. (2015). Examining Unmanned Aerial System Threats & Defenses: A Conceptual Analysis. International Journal of Aviation, Aeronautics, and Aerospace, 2(4). https://doi.org/10.15394/ijaaa.2015.1084