The Militant Drone Playbook
Since January, militants in Iraq and Syria have attempted or executed nearly a dozen weaponized drone attacks against American targets. Most of these involved midsize fixed-wing craft crashing into their targets and detonating, while some involved smaller quadcopter-style drones dropping lightweight munitions, often a 40 mm grenade. None of these attacks have resulted in fatalities or critical damage, but they did prompt the Biden administration to order retaliatory airstrikes against the militant groups behind them.
For years, defense and security leaders have called attention to militants’ increasingly adept use of drones. Earlier this year, U.S. Central Command Gen. Kenneth McKenzie referred to the proliferation of small drones as the “most concerning tactical development” in Iraq since the emergence of improvised explosive devices. But while it is clear that militant drone operations pose a threat, there has been less consensus on the nature and scope of that threat.
Our research leads us to conclude that, while drones give militant groups a new and effective means of tactical disruption, insurgents have been unable or unwilling to use drones for strategic bombing. In coming years weaponized militant drone operations will likely increase, but there is reason to believe that the logic shaping the use of these systems will remain the same. In other words, militants are unlikely to use drone technology to target their opponents’ military centers of gravity or to engage in widespread attacks on civilian targets. As a result, policymakers, soldiers, and security officials should prepare for militant drone operations to expand in degree but not in form. This means developing better counter-drone technologies while still relying on traditional elements of counter-militant strategy.
Pages from the Playbook
The first recorded successful armed drone attack by militants occurred in 2006, when Hizballah struck an Israeli warship with a fixed-wing drone rigged with explosives. Since then, weaponized drone activity has increased significantly — 99 percent of observed attacks have occurred after 2015 — and been dominated by a handful of militant actors in the Middle East. Recent research records 440 drone attacks conducted by militants through 2020. Over 98 percent of recorded attacks have occurred in the Middle East, with two groups, the Islamic State and Houthi rebels in Yemen, responsible for over 80 percent of these.
Our research identifies two prominent patterns in militants’ tactical application of weaponized drones. Together, these indicate that militant groups find drones especially useful for disrupting opponent command and logistics and delaying the movement of military personnel and materiel.
First, militants often use drones for theater air attacks. In some cases, drones are used to support ground operations, providing militants with a combined arms capability. The best-known example of this is the Islamic State’s modifying commercial drones — or engineering its own — to deploy small munitions in Iraq and Syria. The Islamic State routinely and effectively used its makeshift drone arsenal to disrupt enemy fighting positions and troop movements in a number of campaigns, including the Battle of Mosul. In other cases, militants with access to fixed-wing drones have used these as the leading component in a one-two punch of indirect fire — flying below radar to damage enemy air defense systems or military positions in order to open the field for more destructive strikes from missile or rocket systems.
Second, it is common for militants to use armed drones to damage logistic hubs, arms depots, critical infrastructure, and command headquarters behind front lines. Strikes against civilian airports, air bases, factories, and other forms of critical infrastructure disrupt the movement and command of opposing forces. The Houthis, one of the only militant groups possessing military-grade drones, have used this tactic to great effect. From April 2018 to October 2019, the Houthis executed 115 drone attacks. Of these, 62 were conducted against civilian airports or critical infrastructure. Only 27 were conducted against military bases or enemy troops. (The remaining attacks were reported as intercepted or as striking unknown targets.)
A number of militant groups also use unarmed drones strictly for intelligence, surveillance, and reconnaissance operations. While it rarely grabs the headlines, drone-based intelligence, surveillance, and reconnaissance offers significant value to militants for relatively little cost or risk. For example, the Islamic State’s affiliate in West Africa has reportedly used drones to surveil the locations and movement of counter-insurgent forces in northeast Nigeria. Similarly, the Taliban have used drones extensively for years to monitor U.S. and Afghan troop movements.
However, militant groups have rarely used drones for more strategic aims, such as targeting opponents’ civilian populations or undermining their capacity to govern or raise military forces. Even the Houthi forces, who have an unmatched capacity to use long-range drones to strike major cities such as Riyadh, do so only sparingly. And the Islamic State, which regularly commissioned suicide and terrorist attacks in cities that remained under government control, only occasionally used drones to target civilians.
Why is this the case? Sustained strikes that do widespread structural damage would be logistically difficult for militant groups, while terrorist attacks, though logistically feasible, have political drawbacks.
Targeting the enemy’s center of military and political gravity is a challenge for militant groups. Doing so effectively would mean sustaining strikes over time and against multiple targets. This would require fixed-wing systems with greater flight range and payload capacity. It would also necessitate the establishment and defense of drone bases, which would be vulnerable to attack since they could be easily located and targeted. This would require a substantial investment of militant troops, and might prove infeasible unless militants could also invest in air defense systems. A drone fleet would require a reliable logistical supply chain, which would be susceptible to disruption. This highlights how even the most capable militant organizations remain fundamentally different from their state opponents, who have the links to the outside world, reliable sources of income, and territorial depth to sustain strategic strikes.
More surprising, perhaps, is that, with a handful of exceptions, militants have not used drones for terror attacks either. This is true even for groups that have shown a willingness to systematically target noncombatants, such as the Taliban or Boko Haram. Drones would seem particularly well-suited to such a task, since smaller drones could attack many targets and their novelty as a terrorist weapon would amplify their psychological effects. Militants’ calculations about using drones for terrorism appear more political than logistical. Militants engage in terrorism to convince their opponent and civilians that they are ruthless and highly resolved. Terrorist attacks via drone, which lower the risks to perpetrators of being caught or killed, do not signal strong resolve, and instead suggest that the militants are unwilling to put much skin in the game.
Thinking about the future of militant drone use requires understanding both the strengths and limitations of drone technology as well as militants’ political goals and military capabilities. As drone systems become more common in civilian and military environments, militants’ ability to acquire or develop drones will increase. Indeed, more armed groups will likely adopt these systems in coming years. While militant drone use has been highly concentrated in the Middle East, militant groups in other regions of the world (e.g., East and West Africa and Central Asia) will likely soon incorporate weaponized drones into their tactical operations. This is especially likely for groups with operational connections to transnational movements such as the Islamic State and al-Qaeda. Other factors may create greater opportunity for their use as well. The anticipated increase of urban warfare is particularly worrisome, as urban terrain is especially well suited to small drone use.
While we expect the use of armed drones by militant groups to increase and expand, the pattern of militant drone use is unlikely to change soon. Even with larger drones, targeting an adversary’s center of gravity will still require militants to control and defend territory and access global supply chains, areas where state opponents tend to have large advantages. And militants may find that alternative airborne weapons systems — rockets and missiles, for instance — remain better suited to the task of producing destructive effects against strategic targets. Therefore, we believe that militants will continue to view drones as a useful adjunct to their existing military repertoires, using them to assist in targeting forces on the battlefield, to harass command and logistic hubs, and to disrupt the supply and movement of adversaries’ soldiers and materiel.
What can state actors do to counter this threat? On the one hand, our analysis offers good news — in the near future, most militants are unlikely to be capable or willing to develop fleets of drones to pursue strategic objectives. The bad news, at least for state militaries, is primarily on or near the battlefield. It has proved difficult to develop military systems that can reliably intercept smaller drones. The development of counter-drone technology is and should remain a priority. But even improved counter-drone technology will only help mitigate the threat, and militants will be quick to adapt. This means that, even in an era of drone warfare, traditional elements of counter-militant strategy will remain essential: rooting out the deeper militant drone threat means disrupting supply chains, targeting sources of revenue, finding and engaging combat and support units, and cutting militant forces off from any territorial safe havens.
Austin C. Doctor is an assistant professor of political science at the University of Nebraska at Omaha and a member of the executive committee of the National Counterterrorism Innovation, Technology, and Education (NCITE) Center, a U.S. Department of Homeland Security Center of Excellence. He earned a Ph.D. in political science from the University of Georgia. He writes on militant organizations, terrorism, armed conflict, and political instability. You can find him on Twitter @austincdoctor.
James Igoe Walsh is professor of political science at the University of North Carolina at Charlotte. He holds a Ph.D. in international relations from American University. His research interests include technology and conflict, human rights violations, and forced displacement and return. His book, Combat Drones and Support for the Use of Force, is available from the University of Michigan Press. His work has been supported by the Army Corps of Engineers, the Department of Homeland Security, and the Minerva Research Initiative and Army Research Office. You can find him on Twitter @jamesigoewalsh.