The battle for Mosul has been a wakeup call for drone defense. In late 2015 it emerged that ISIS had developed the capability to deliver lethal payloads using modified commercial drones, but in Mosul the attacks reached a new pitch in February with dozens of attacks a day by drones dropping grenades.
The drones were mainly consumer-grade quadcopters, the type hobbyists use for aerial photography. ISIS has previously used these for reconnaissance and artillery spotting, but the latest batch were equipped with a simple release mechanism to drop a modified 40mm grenade fitted with tailfins. The grenades were ‘High Explosive Dual Purpose’ variety which can piece two inches of armor plate, as well as scattering lethal fragments out to a fifteen-foot radius. The drones hovered over a target at an altitude of three hundred to a thousand feet, and dropped grenades with considerable accuracy, scoring direct hits on Iraqi military Hummers and other targets.
One Iraqi officer said that they were seeing more than seventy drone sorties a day, and a BBC correspondent said it was “almost raining bombs.” There were many casualties; in one attack nine civilians were killed while waiting for aid. Lt Col. Arkan Fadhil, injured in one attack, memorably commented that “It’s annoying, with someone always tossing a grenade on you.”
After several urgent requests, the US supplied a vehicle-mounted jammer (reported to be the system developed by UK company Blighter Systems) which reduced the drone attacks in Mosul to zero. Commercial drones operate on known frequencies and have no resistance to jamming; when they lose the control signal they automatically return to their launch point or (if GPS is also jammed) land in place. However, ISIS drone attacks have continued in other areas around Mosul.
Jamming is not a panacea for drone attacks. In a comparable situation in Ukraine, rebels used Russian-made jammers to bring down Ukraine’s improvised drones (as well as US-supplied RQ-11 Ravens). The Ukrainians responded with more sophisticated, jam-resistant drone communications. Many ISIS drone workshops have been uncovered, and it is likely they are working on more robust control systems.
Other developments in the drone wars over Mosul are likely to be rolled out on a large scale in future conflicts:
ISIS are known to have chemical weapons, and drones and chemical weapons are an obvious combination for terror attacks. David Cameron, then British Prime Minister, mentioned intelligence reports of ISIS plans for a ‘dirty drone’ to spray radioactive material in 2016. In April, Kurdish forces in Syria claims to have shot down three ISIS drone carrying what were described as ‘bottles of toxic material.’ This cannot be verified, but it is likely that ISIS will experiment with drones for chemical attacks.
There were several reports of ISIS drones firing rockets; two schoolchildren were killed in one such attack. ISIS have long expressed an interest in a drone able to fire guided missiles (a poor man’s version of the US Reaper-Hellfire combination). This would require considerable development, and the weapon involved is more likely to be an unguided rocket or RPG, like those tested from Russian multicopters. This would potentially give a long stand-off range – possibly a longer range than some jammers, posing a serious challenge for defenders.
Some have dismissed the ISIS drones as a mere nuisance because of their limited payload. A single grenade can only do limited damage, especially against large armored vehicles. Larger drones are in prospect. A memory stick in one captured ISIS headquarters contained documents from ISIS drone engineer Fadhel Mensi with details of ‘Project Ababil’ , a fixed-wing drone able to carry forty pounds of explosive. A warhead this size could destroy heavy tanks and fortified positions, and may have the accuracy of a guided missile.
ISIS drone operations have only been carried out ion daylight, but the Iraqi Federal Police have built their own improvised drone bombers fitted with thermal imagers, allowing them to operate at night. Thermal imaging technology is now becoming more widely available, with companies like FLIR producing systems designed to be carried by small DJI drones. Export controls are in place but some such devices will find their way in to the black market. Night attacks by drones will be more difficult to handle, especially as drones (unlike humans) have little thermal signature.
It became a joke in Mosul that the drone attacks were like weddings – everyone fired into the air at once. Some drones were brought down this way, though they were frustratingly difficult targets. On early April, Kurdish reported that ISIS were using ‘fake drones’ – carried on a long line underneath a real drone – to draw fire and exhaust ammunition supply. This may have been inspired by a famous Halloween prank of a drone carrying a ‘ghost’ on invisible wires; as well as wasting ammunition it might distract defenders from the real drone dangers.
The precision of the drone attacks in Mosul, in some cases even hitting moving targets, came as a surprise, and accuracy is likely to increase. In WWII, the US most secret weapon next to the atomic bomb was the Norden computing bombsight, an elaborate arrangement of gyros, lenses and mechanical calculator which vastly improved bombing accuracy. Small drones have all the hardware needed for precision bombing, all that is needed is software. Some ISIS videos (this one at 3:43 onwards) show moving objects (people and vehicles) apparently being picked out automatically and tracked with a moving circle; the trajectories of falling bombs are similarly highlighted and tracked. These effects were probably added in post-production, but similar software is already used by US tactical drones. Future drone may be able to track targets and release grenades to hit them, even while maneuvering – and may be able to pick out targets automatically.
Some news reports described occasions when three to five drones attacked as a group. In other cases, one drone acted as a decoy to distract defenders from the direction of the real attack, indicating a high level of co-ordination. Larger numbers were also used, with one US officer saying that ISIS had shown an ‘almost swarm-like capability’ in some actions. The US military is developing its own drone swarms (the DoD’s Perdix and the Navy’s LOCUST); a single operator can control a swarm of many drones, enough to overwhelm defenses by sheer numbers. Swarming software is complex, but is being developed for civilian use and is likely to become widely available. This would open up the possibility of simultaneous coordinated attacks by hundreds of drones at a time.
Mosul was the start of a new era in drone warfare: a crowd-sourced, mass-market drone war in which smart weapons were available to all sides including non-state actors. The next wave is likely to see smarter and more effective drones, incorporating some or all of the technologies listed above. Existing counter-drone defenses are likely to prove inadequate. The risk is that US forces may end up on the wrong side of an asymmetrical conflict in which the only casualties on the other side are drones.
---- David Hambling is a Scout Warrior contributor