Violent non-state actors have increasingly been making use of unmanned aerial vehicles (UAVs). Initially, this was limited to intelligence, surveillance, target acquisition, and reconnaissance (ISTAR) missions. More recently, some terrorist organizations – among them, the Islamic State and Hezbollah – have extended their use of UAVs to include the deployment of Improvised Explosive Devices (IED) in warzones. Now, the threat of UAVs being used in attacks in Europe or North America is rising.
Since 2001, the war on terror has witnessed the gradual emergence of a new weapons system: the Unmanned Aerial Vehicle (UAV). Efficacy, affordability, and low political costs have increasingly made UAVs the weapon of choice against violent non-state actors. Simultaneously, commercial UAVs – considerably smaller and cheaper than military versions – have become widespread in industrialized societies. Their applications range from agriculture to the filming of sporting events. However, violent non-state actors have quickly learned how to adapt this technology to their advantage.
Warzones: the UAV testing ground
The use of UAVs has generally been limited to warzones – such as Syria, Iraq and Ukraine – and areas characterized by high levels of illicit activity and drug trafficking – such as Central America. Being cheap and easy to deploy, UAVs are well suited to the nature of modern asymmetric conflicts.
Generally speaking, UAVs have been use by non-state actors in intelligence, surveillance, target acquisition, and reconnaissance (ISTAR) missions. More recently however, commercial UAVs have been weaponized and used in lethal operations by a small subset of violent non-state actors.
These include paramilitary factions in the conflict in Eastern Ukraine – both separatist and pro-government forces – and militant groups in Syria and Iraq (the Islamic State, Hezbollah, and Saraya al-Khorasani). Hezbollah has also repeatedly tested Israeli defense systems, attempting to penetrate Israeli airspace with UAVs.
There are indications that UAVs are being deployed in increasingly sophisticated ways. In one remarkable episode, an ammunition deposit was blown up in Eastern Ukraine with the use of a small drone carrying a 1-pound thermite grenade. Just in the last few days, Russian forces reported a swarm drone attack against the Khmeimim air base and the Tartus naval base in Syria.
Risk of UAV use in terrorist attacks
The first attempted use of a UAV by a terrorist group reportedly goes back to 1994, when the apocalyptic cult Aum Shinrikyo unsuccessfully aspired to disperse sarin gas through remotely controlled helicopters. However, criminal and terrorist organizations began experimenting with this technology in earnest starting from 2001. Now that the capability to deploy UAVs has been extensively proven on the battlefield, the risk of their use beyond theatres of warfare needs to be seriously considered.
Indeed, the Islamic State has repeatedly encouraged its affiliates to carry out attacks by means of UAVs across Western countries. Commercial, off-the-shelf UAVs are largely available and economically affordable. Some of these models are capable of carrying sufficient payloads to be weaponised. Modifications are possible that could increase their range, altitude, and payload capacity further increased; adapting UAVs to deploy small IED is not an insurmountable technical hurdle. There are concerns about UAVs being capable of deploying chemical, biological, and radiological materials.
That said, initial attempts to deploy UAVs in urban context in Western countries would most likely be more rudimentary. Limited resources, capabilities and experience will probably restrict the options for lone attackers or small autonomous terrorist cells. After all, even in warzones, the use of UAVs followed a linear development that saw their deployment advancing from simple ISTAR mission to attacks in swarming formations, as their operators learned and adapted to the technology.
There is also likely to be a persistent motivation for terrorist groups to attempt more sophisticated attacks in Western countries, involving multiple UAVs. This would fit with the goal of achieving a spectacular and devastating terrorist attack.
Potential targets range from sporting events to airports
Soft targets are the most likely, and sporting events could well be an optimal target – one that terrorists have repeatedly struck, or attempted to do so. The rationale behind terrorists’ interest in targeting sporting events is straightforward: they are mass events attended by large crowds in restricted spaces, and they attract a lot of media attention. The same logic applies to (indoor or outdoor) music events – another terrorist target of choice. Significantly, there have already been minor incidents involving unauthorized UAVs at sporting events.
What might such an attack look like? Most commercial drones carry limited payloads – up to 20kg for heavy lift drones. However, even a small payload – from few hundred grams to a couple of kilograms – detonated among the crowd could result in mass casualties. The resulting chaos and panic could give rise to a stampede the consequence of which could be catastrophic – as the 2017 stampede in Turin following a false alarm demonstrated. Resorting to UAVs would circumvent security measures in place, such as metal detector, K9 units or concrete barriers. Commercial UAVs are increasingly used to film sporting events, thus augmenting the chances of a rogue UAV “blending in” and approaching its target unchallenged.
Hard targets and infrastructure would prove more difficult to strike by means of UAVs, despite some reports arguing the opposite. The above-mentioned attack on a Ukrainian weapons stockpile should be seen as an exception, since it aimed at downgrading an opponent’s military capability in a conflict zone, rather than being a terrorist attack. Small terrorist cells in western countries would be discouraged by the additional security measures, security protocols, and even in some cases no-fly zones around strategic infrastructure. Moreover, commercial UAVs’ smaller payloads would only cause limited damage to buildings. Lastly, operators must remain relatively close to UAVs, exposing themselves and potentially jeopardizing their missions if these are attempted in remote, uncrowded areas.
The nature of the challenge with hard targets also varies according to the type of facility. Large infrastructure, like bridges or dams, could withstand the blast generated by the detonation of the UAVs’ limited payloads. Larger payloads or coordinated attacks involving several UAVs would be necessary, increasing the risk of detection. Electrical grids or water supplies might be more vulnerable. Yet these fall short in terms of the theatrical characteristics that terrorists seek to achieve in an attack.
Chemical plants and nuclear facilities might be a different case. As reports show, UAVs maneuverability and small size could enable them to circumvent even those barriers put in place to withstand the collision of a hijacked aircraft. Far from being able to bring the entire structure down, UAVs could still be used to trigger instability.
Last but not least, airports represent a further target. Countermeasures like geofencing, cyber warfare and drone-hunting eagles should decrease the likelihood of UAVs successfully approaching an airport – or any other hard target. Yet the increase in near-miss events between aircrafts and UAVs in proximity of the airports is discouraging in this regard.
Insufficient regulation and rapid technological change increase the risks
Commercial UAVs are not subject to the export regimes covering military export controls. Therefore, their trade is not restricted by any major international agreements – and as a result, the technology has not been prevented from falling into the hands of the above-mentioned non-state actors.
Governments of western countries – mainly EU and USA, as the primary potential targets of terrorist UAV attacks – are of course well aware of the threat. Indeed, a wide range of countermeasures – including net-shooting guns, anti-drone radio signal jammers, laser systems, as well as the above-mentioned geofencing, drone-hunting eagles – is currently being developed. These governments have also been working on setting up legislative means that would, ideally, prevent the misuse of UAVs.
However, such provisions fall short, as most regulate generic aspects of UAVs: registration, licensing, and the “line of sight rule”. Some regulations include the civil and criminal liability of the operators – in the case of the UK, or flight authorizations – as in Italy. But even the fullest implementation of such regulations will most likely not suffice to prevent the misuse of UAVs. The technology keeps evolving and the barriers to obtaining smaller, more efficient, and even autonomous UAVs are being overcome. In particular, the ability to use 3D printing to produce drones or parts thereof will pose additional risks. Under these circumstances, the use of UAVs for terrorist attacks is most likely a question of “when”, not “if”.