Earlier this year, the Yemeni-based Houthis launched a drone attack on an oil storage facility in Abu Dhabi. The attack killed three and injured six. Following the attacks, UAE officials thwarted various other Houthi drone attacks and warned of the rising drone threat.
In addition to the Houthis, jihadi groups such as the Islamic State (IS), Hamas, and Hezbollah have used drones for reconnaissance, propaganda, and attacks, with IS being one of the most proficient in its use during the height of its powers from 2015 to 2017.
While the recent attacks have cast the militant use of drones into the limelight, the questions that remain to be asked are “how likely is a mass casualty terrorist attack involving drones” and “are drones really a militant game changer?”
Houthis Use of Drones
Between 2016 and 2021, the Houthis were reported to have conducted more than 4,000 drone and missile strikes on Saudi targets.
The first type of drone they began using was the commercially available DJI Phantom quadcopter, alleged to have been stolen from a local TV station.
From 2017 onwards, the rebels began using larger, fixed-wing aircraft-type drones in attacks. These included the Qasef-1, Qasef-2k, Sammad-2, and Sammad-3, which hinted at Iranian involvement.
The British-based think tank Conflict Armament Research noted that these drones were manufactured in Iran and supplied to Yemen. Other evidence suggested that the Houthis learned to manufacture DIY drones using a mix of local parts and higher-end components smuggled into Yemen.
Islamic State Use of Drones
IS, on the other hand, has primarily used commercial quadcopters. The group had also attempted to reverse engineer American and coalition propeller-driven aircraft-type drones that had either been shot down or crashed in Iraq and Syria, but it is unclear whether they succeeded.
Much of IS’ drone use was initially for surveillance, to direct suicide bombers to targets, and to shoot aerial imagery for propaganda videos. IS had a dedicated unit and a highly sophisticated network for procuring and developing drones.
In late 2016, IS began crudely weaponizing commercial quadcopters by using them to drop small bombs on Iraqi and coalition soldiers by attaching plastic tubes fitted with small munitions to the base of the drones.
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While this had a limited casualty rate, it had a substantial psychological effect on ground troops and was effective in destroying localized targets such as tanks and small military convoys.
In 2017, IS was reported to have launched 60 to 100 drone attacks per month.
Drone Use in Terror Attacks
Despite their relative ease of availability, the use of drones in attacks has been largely confined to conflict zones.
An important factor in the militant use of drones is territorial control. The Houthis control a considerable amount of western Yemen centered upon Sanaa, enabling the group to ensure a sustained supply chain of materials needed for the procurement and development of these weapons.
Territory also enables the rebels to launch frequent, consistent attacks at distant targets. The Houthi Qasef and Sammad drones, which have a range of 200 to 1,500 kilometers (125-930 miles) and endurance of approximately two hours, enable launches against foreign targets from the cover of the Houthis’ own territory.
IS’ offensive use of drones was most dominant at the height of their presence in Iraq and Syria. However, without territory, groups lack the safe space required to procure and innovate with drone technology.
Drones’ Access and Capability
The Houthis have access to more sophisticated drones due to external influences. While still considered low-tech, the Qasef and Sammad drones have a higher payload, range, and endurance than hobbyist drones, making them more lethal.
Commercial, off-the-shelf drones have a limited payload owing to their small size. Quadcopters can only carry around 1 kilogram (2.2 pounds) of excess weight (which in the case of weaponization means explosives), while some larger ones can hold a maximum of 5 kilograms (11 pounds).
This makes them more suitable for targeted assassinations and small-scale attacks. In November 2021, three Shiite militia groups employed two off-the-shelf quadcopter drones rigged with explosives in an attempt to kill Iraqi Prime Minister Mustafa Al-Kadhemi in Baghdad.
One of the drones failed to detonate, while the other had inflicted damage on a car and the interior of the prime minister’s house. No serious injuries were reported.
Aircraft-type drones deployed by the Houthis can carry a much higher payload of between 30 to 45 kilograms (66-100 pounds) and are thus more lethal.
A successful drone attack is also dependent on external conditions such as weather and wind speed. These add an extra layer of complications in carrying out attacks compared to conventional attack methods.
A Game Changer?
Drones remain a major problem for security services because they fly at much lower altitudes than aircraft and are thus able to avoid detection by most radar systems designed to target objects flying at higher altitudes.
Furthermore, the ease with which commercial drones can be procured and modified into weapons reduces the accessibility threshold to actors with malicious intent. For example, some Houthi drones are believed to have been duplicated from German civilian technology with the help of Iran.
Militants are likely to view drones as a useful adjunct to their current arsenal. While drones will likely be a limited game changer, they do add a level of complexity to military operations.
Aircraft-Type Drones vs. Commercial, Off-the-Shelf Drones
The threat arising from drone use by militant groups can be viewed as two-pronged.
First, there is the threat arising from more sophisticated fixed-wing aircraft-type drones like the ones used by the Houthis. These drones will remain a significant threat in conflict zones such as Yemen.
Thus far, the Houthis have focused on strategic targets such as oil facilities, defense establishments, and airports. However, this does not discount the possibility of drone attacks on more highly populated civilian targets.
Secondly, there is the threat from off-the-shelf drones such as commercial quadcopters. These instruments have a more limited lethality due to their lower weight, endurance, and range. Nevertheless, they may be an attractive option for lone actors or cells in low-scale localized attacks or targeted assassinations.
These drones are widely available, and weaponizing them does not require much skill and capabilities.
— Ahmed Rasheed (@Ahmed_Rasheed_R) January 4, 2022
Most IS militant cells outside the Middle East have demonstrated strong capabilities in developing improvised explosive devices. Mounting them onto commercial drones does not require much more technical skill, as some have described it to be something that a “sophisticated high schooler could put together.”
In fact, there have been a number of foiled IS-linked plots in Indonesia and Malaysia employing commercial drones.
Thus, the proliferation of dual-use technology such as drones must be regulated appropriately to prevent it from being misused by malicious actors, and governments must remain cognizant of the threat they pose.
Rueben Dass is a Research Analyst with the International Centre for Political Violence and Terrorism Research, a constituent unit within the S. Rajaratnam School of International Studies in Singapore.
His research interests include terrorism and counter-terrorism in Southeast Asia; Chemical, Biological, Radiological, and Nuclear (CBRN) terrorism; and terrorist use of technology and unconventional weapons.
The views and opinions expressed here are those of the author and do not necessarily reflect the editorial position of The Defense Post.
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