For all the amazement that swarms of consumer-grade drones provoke—flying in choreo­graphed clusters to form logos, pictures, and even QR codes in the sky—they’re also a subject of some strategic concern among national security experts. Drone swarms, one analyst says, are the new WMD (weapon of mass destruction); “slaughterbots” are the new nightmare technology, says another; one prominent media account describes “sinister” flocks of “really creepy” drones buzzing residents in rural areas and raising fears of mass surveillance, or worse.

Of course, drones by themselves are not new. However, what is new is that rogue states, terrorist groups, and other malevolent actors around the world are seeking weapons that can do less damage but can still rival a WMD in effect. During the Cold War, strategic analysts surmised that states would want WMDs for widespread destruction. Yet in the last three decades, several states have used chemical agents—canonical WMDs—in peacetime for assassination of individuals.

North Korean dictator Kim Jong Un is thought to have assassinated his half brother with VX nerve agent in 2017. A year later, Russia was suspected to have used a Novichok chemical agent in Salisbury, England, in a failed assassination attempt of a former Russian spy and his daughter. The U.S. intelligence community has recently linked the Russian government to the attempted assassination of Russian dissident Aleksei Navalny in 2020 with a Novichok agent.

Geopolitical actors have shifted their desired outcomes because they’re already getting the strategic impact they want at lower levels of destruction.

Think of this as a new category of armament similar to WMD—also scalable, as the chemical agents above have been used for more targeted killings, but more accessible and with similar strategic impact. Call this new category, as it were, weapons of mass agility (WMA).

For the above reasons among others, nefarious states and violent nonstate actors may be increasingly attracted to WMAs. So strategists need to be aware of this trend to counter its threat.

Weaponized consumer drones, for instance, have the potential to spark fear among the general public. “Really creepy” was used in response to those drones that hovered but did nothing, at least that anyone could discover. What might public reactions be if this consumer technology was used for more malevolent ends? In that sense, weaponized commercial drones might therefore factor into the strategic calculations of national and international leaders in similar ways as cyber, biological, and chemical weapons.

In March 2021, online publication The War Zone revealed the results of an extensive investigation of drone flybys around naval ships. In July 2019, the U.S. Navy documented the presence of a drone swarm near the USS Kidd destroyer several times over a period of a few days. As many as six drones engaged in complex maneuvers in low visibility conditions, buzzing the destroyer, which was traveling at more than 29 kilometers per hour (18 miles per hour).

The drone activity unleashed an internal investigation involving the Navy, FBI, and U.S. Coast Guard and receiving attention from the Chief of Naval Operations. The War Zone uncovered details of the strange events through FOIA requests of the Navy’s deck logs and internal communications and reconstructed the scenarios using ship location data. No viable explanation for the drones could be uncovered.

Simple math illustrates the potential of drones against a destroyer. It costs the U.S. Navy as much as US $936 million to build a single Arleigh Burke–class destroyer. Meanwhile, a Turkish ­Bayraktar TB2, the unmanned combat aerial vehicle (UCAV) most recently used to great effect by Azerbaijan in its conflict with ­Armenia, carries a payload of 150 kilograms of laser-guided munitions. The TB2 costs only somewhere between $1 million and $2 million each. Assuming the higher end for each weapons system, a country could acquire 468 UCAVs for the price of a single guided-missile destroyer.

When recalling the al-Qaida-led suicide bomber attack against the USS Cole destroyer in 2000, it doesn’t require a great stretch of the imagination to see the strategic advantage in smaller, cheaper, smarter systems over exquisitely designed and expensive platforms such as fighter jets, aircraft carriers, and destroyers. It took only a small boat laden with about 180 to 320 kg of C4 explosives to blast a large hole in the Cole, killing 17 sailors and injuring 37 more. Though the vessel was not destroyed by the attack, it was removed from service for nearly three years for repair. A Ford-class aircraft carrier costing $12.8 billion per ship offers up an even more lucrative target than a destroyer. Although consumer drones remain far less capable than military-grade UCAVs, their payload, performance, and autonomous capabilities are growing quickly.

The impact of drones also extends far beyond their prospects for causing damage to expensive military targets.

The potential of consumer or commercial drones harming world leaders became immediately evident when a protester hovered one close to German chancellor Angela Merkel at a campaign rally in 2013. Leveraging their agility, countries have often used UCAVs to deliver lethal strikes on specific targets, most recently by the Moroccan armed forces to kill the leaders of a separatist group. In 2018, an unidentified nonstate actor used two explosive-bearing commercial drones in the attempted assassination of Venezuelan president Nicolas Maduro.

The most consequential WMAs could potentially rise to the level of a WMD, by causing mass casualties and destruction. Possible attacks include using autonomous drone swarms against a soft target like a stadium full of people or dispersing drones bearing biological or chemical agents over a large area. Since the perils of WMD have been around for decades, though, such scenarios are unfortunately not new. And since malevolent actors may still be able to achieve their desired strategic impact at lower levels of destruction with WMAs, these actions may continue to be low probability.

However, the close calls and early salvos of maliciously targeted commercial drones have so far provided only a hint of what is to come. Technologists and engineers who work on drones need to be aware when they develop applications that might be weaponized and exploited for deadly effect. And policymakers and military strategists need to be equally vigilant in defending against a highly agile new threat that, while its use has, gratefully, been limited to date, its potential for danger will continue to increase as commercial, off-the-shelf drone technologies mature and proliferate.

About the Author

Natasha Bajema is the director of the Converging Risks Lab at the Council on Strategic Risks, in Washington, D.C.

This article appears in the June 2021 print issue as “Weaponized Drones: Know Your Enemy.”

This article is an adaptation of a recent the author wrote for the Council on Strategic Risks, “Weapons of Mass Agility: A New Threat Framework for Mass Effects in the 21st Century.”