Easily available, difficult to detect and hard to intercept, small drones pose a challenge to even the world’s most advanced militaries.
When Iraqi tanks had ISIS cornered during the battle of Mosul in 2017, the extremists disabled a US-made M1A1 – a 60-tonne behemoth and one of the world’s most formidable armoured vehicles – by using a makeshift drone to drop a small grenade next to the commander’s hatch.
A drone costing less than $1,000 was able to defeat a tank worth $4 million in an incident that underscored how effective even civilian drones could be in the hands of terrorists who can easily turn them into weapons.
Terrorists and paramilitary groups across the region, from Yemen’s Houthi rebels and Iran’s Islamic Revolutionary Guard Corps to Hezbollah and Iraq’s militias, have come to regard drones – whether purpose-built or weaponised – as a vital tool in their attacks aimed at destabilising more powerful foes.
But a host of new ideas and technology promises to turn the tide against the use of low-cost drones in conflicts and give state militaries new ways to provide security against unconventional attacks.
From high-tech laser beams and microwave radiation attacks, to bespoke radar systems and electronic signal jamming, modern militaries will be able to call on a whole arsenal of ways to counter the drone threat.
Older systems are also being re-purposed, from fighter jets with powerful "look down, shoot down" radar and helicopters are being given new weapons to hunt unmanned aircraft.
Some new systems are already being used to thwart attacks in the Middle East.
New ways to counter drones
As drone attacks have become more common – including those targeting Saudi Arabia, US forces in Iraq and recently, the UAE – some of the world’s best defence technology experts are competing to defeat the threat.
No solution seems too outlandish.
In May, US tech company Epirus claimed that its high-powered microwave system disabled 66 small drones in mid-flight, frazzling their electronics.
In June, Israel’s Elbit systems took down several unmanned target aircraft using a laser mounted on a light aircraft.
Companies are also already fielding drones that hunt other drones as well as a host of new, bespoke radar systems and lasers to stop the small aircraft.
Some of these ideas have been years in the making.
The US Defence Intelligence Agency has held an annual counter-drone exercise since 2002 called Black Dart, which has grown into a major contest between contractors.
But it is only recently, after a spate of terrorist drone attacks that US efforts have gone into high gear.
Black Dart’s live fire exercise has led to the deployment of a counter-drone laser system on a warship, among other innovations.
Could the days of terrorist drone swarm attacks be over?
“In the case of counter-drone systems, there is no silver bullet,” says Austin Doctor, an expert at the US National Counterterrorism Innovation, Technology and Education Centre.
“The variety of drone types deployed by militant forces, and the demonstrated creativity of militant actors suggests that an effective single system solution will remain elusive,” he says.
“Instead, a sustainable approach will likely rely on a suite of affordable integrated technologies.”
The landscape of counter-drone tech suggests this is exactly what is happening – an array of different methods working in tandem to counter the different drone options available to terrorists.
Why are drones such a problem?
In part, the challenge has arisen from the rapid proliferation of civilian technology – for example, Houthi-drones thought by the UN to have been made with Iranian help had copied engines made by a German civilian company.
One of the main reasons why drones are so difficult to defend against is that they fly extremely low, while most defensive radars are designed to detect high-flying aircraft or missiles.
Imagine a radar beam aimed at the sky searching for a ballistic missile or enemy plane. The missile flies on an arc that can reach tens of kilometres into the atmosphere – or even thousands of kilometres into space. Fighter planes like the F-15 can cruise at 65,000ft, nearly 20 kilometres high.
Now, imagine the radar beam is lowered to detect something low-flying. At some point, the curvature of the Earth, as well as valleys, mountains and buildings come into play.
Just as a torch cannot shine around a corner, radar beams cannot curve around the Earth.
That means an attacking missile, plane or drone can creep up on the enemy using these blind spots called the “radar shadow”.
At very low altitude, drones can hug the terrain in a way that would require extreme skill and endurance for human pilots.
Aside from the radar horizon challenge, most drones have a small radar signature due to their size, and a low heat signature, making them harder to detect using infrared sensors.
But new approaches are eroding this advantage.
How drones are already being intercepted
Existing air defence systems have already been used to counter drones.
The American C-Ram system, which fires a stream of high-explosive cannon shells at 4,500 rounds a minute, was originally designed to intercept rockets and artillery. It has already been used to shoot down drones attacking US forces in Iraq, but comes with risk if used in populated areas.
Similarly, the US PAC-3 Patriot missile systems, designed to intercept missiles and aircraft, can now also be used to take down drones, albeit at a high cost per interception.
In Israel, the Iron Dome system uses AI-assisted technology to shoot down rockets, but has also been used against drones.
Again, the high cost of using such a system to defend against drones – each interceptor missile is said to cost about as much as a brand-new Nissan Patrol ($50,000) – means the Israelis are interested in finding a cheaper system.
Other approaches involve seeking out drones as they creep through the radar shadow – the blind spots in air defence systems often exploited by drones.
The Raytheon Coyote Block 2 for example, uses drones to hunt drones.
It is likely that Coyote has already been used at Al Asad airbase, a joint Iraqi-Coalition air base in western Iraq which has frequently been attacked by “kamikaze drones”, assaults widely attributed to Iran-backed militias.
New electronic jamming systems are in operation. Michael Knights at the Washington Institute for Near East Policy, a think tank, believes they have probably defeated drone attacks in Iraq.
When photographs of downed drones appear in Iraq, it is sometimes possible to assess how they are dispatched, Mr Knights says.
There can be visual clues that show a drone was brought down by a laser.
“Each type of kill has a thermal component. What you want to see is a burn hole on the bottom front," he says, referring to the use of laser systems.
In June, US forces in Iraq said they had deployed Claws, a high-powered laser mounted on the back of a lorry, to tackle smaller quadcopter armed drones.
Turning the tide
The deployment of Coyote and similar systems could be a serious hindrance to military operations of Iran’s proxies.
In June 2020, a UN report blamed Iran for supplying drones to Houthi militias in Yemen, which destroyed critical oil infrastructure at Abqaiq, Saudi Arabia, in September 2019.
In the promotional video for the Coyote system, one of the drones destroyed has a triangular, or “delta” wing shape, similar to the drone type used at Abqaiq and in a lethal attack on the MT Mercer Street commercial ship in July.
“They’re getting quite annoyed,” says Mr Knights, referring to Iran-backed groups.
“We had them claiming fake drone attacks, as it doesn’t produce visible evidence of interception. So, better to claim a false attack than undertake a real one."
If drones used by Iran-backed groups represent a cheap option, it makes sense to counter them with inexpensive technology.
“Narrowing the cost ratio remains one of the primary challenges to developing an effective and sustainable counter unmanned aerial vehicle infrastructure,” Mr Austin says. Compact laser weapon systems, which are cheaper than missile interceptors, are a big step forward, he says.
Raytheon emphasises the cost-effectiveness of new systems, saying Coyote interceptors could eventually cost as little as $5,000 each, leaving systems like the $1bn Patriot to defend against more expensive, fast moving ballistic missiles.
But some analysts caution that even if militias take a hit from the use of counter-drone systems, the threat the groups represent will persist.
“I feel we shouldn't fall into panacea talk,” says Phillip Smyth, a security analyst who specialises in Shiite militancy and proxy groups across the region.
“The US and Israel have plenty of anti-rocket and anti-guided missile systems. However, the weapons continue to get launched and new strategies with old weapons systems will be developed.”