Drone Swarms: Bracing up with The New Threat
Lt Gen (Dr) V K Saxena (Retd), PVSM, AVSM, VSM, Distinguished Fellow, VIF

(This article linked with a previous article titled, Drone Swarms - a Growing Lethality. Where is the world? Where are we? published on the VIF portal on 06 Apr 20201.While the said article highlighted the growing lethality of the drone swarms, the current one deals with the emerging measures to counter the same.)

A New Threat Knocks

On 05 Jan 2018, for the first time in recorded history, a set of 13 drones, appearing rudimentary in design and appearance, attacked the Russian Air Base at Khmeimim and their Tartus naval facility in West Syria2.

A strong air defence power like Russia, even after committing its frontline Surface-to-Air Missile (SAM) Pantzir, worth millions of dollars, could kill only seven of the cheaply made drones that attacked the air base while the cyber unit, which tackled the other six, could soft kill only three. Three landed intact.

On 14 Sep 2019, ten weaponised robots (one other report says 18 robots and 7 cruise missiles) attacked the Saudi oil facility at Abqaiq and Khurais. A whooping 5.7 million barrels of oil got stalled. The blow was so severe that it actually halved the oil output of the country….


Important to note that the drones in action in the above two incidents were a miniscule, just 13, 10 etc. What if this number is 100 or may be many times this figure? The cumulative catastrophic effect will be simply unimaginable!

Swarming drones are the latest arsenal in the tools of aerial warfare which are posing a grave and an unprecedented challenge to the defenders.

This article examines why this challenge is unprecedented and what is happening in the defenders’ camp to brace with the new threat.

Why the Challenge is Unprecedented?
Building the perspective

It all started with single-propeller driven crafts carrying their valiant gunners who tried to train their machine guns on ground targets in a hit-n-trial mode. This was air threat at T0!

Times changed over decades, the aircrafts transformed into deadly fourth, fifth (and now sixth) generation machines armed-to-the-teeth, the attack helicopters surprised defenders by flying in the nap-of-the-earth and hit their targets suddenly at close ranges, the anti-radiation missiles or ARMs sounded a death-knell to all sensor-based equipment, the needle-sharp cruise missiles picked and destroyed their targets accurately, a whole generation of smart, intelligent and precision-guided munitions came up over time…. Times changed.

While the times changed over six-seven decades and more, it still remained under one class. The class was ‘conventional air attack’.

To tackle this attack, over the same six-seven decades or more, came up a whole family of air defence weapons based on ground, sea and air and integrated as one whole.

‘The Conventional Attack-Defence Cycle’

Based on the above, the attacker-defender duel which was the norm till recently, had a typical signature. The same roughly unfolded like this:-

  1. The attacker will put together an aerial threat package consisting of aircrafts, attack helicopters, ARMs , cruise missiles and more packed with state-of-the art munitions and enabled by best of avionics technology providing such capabilities as long range, deep strike, precision, standoff kill capability, stealth muscle and more. The munitions included both the hard kill as well as soft kill.
  2. The above threat package will be executed in very many different profiles, techniques and packages as to overwhelm the defences, one way or the other.
  3. The defender on the other hand, will put up strong defences integrated over land, sea and air. Besides air defence aircrafts, such defences will comprise of air defence guns of various hues and a whole family of SAMs stating from a very short range and others going upto ranges of hundreds of kms. All these knitted together by a strong and an autonomous Battle Management Command and Control System.
  4. The basic pattern would be to detect the air threat as far forward as possible, identity it to be friend or foe, prioritise the attack based on immediacy and lethality and bring to bear upon it seamless and successive fire, shifting from weapon to weapon as the threat drew inwards to its intended target.
The Game changers

The above battle sequence saw a paradigm change with the emergence of two very special weapons; Hypersonic and Drone Swarms.


Hypersonic weapons are two types; Hypersonic Cruise missiles (HCM) and Hypersonic Glide Vehicles (HGVs). What is so different about them?

  1. HCM and HGVs are capable of flying at speeds of Mach 5 (approx. 5000Km /h). To get a better grasp of what it means, this speed means that the vehicle is flying at 1.6 km/sec. Such a weapon has a capability to strike anywhere in the world in less than one hour!
  2. As if the above was not enough, Mach 5 is no more the ‘going figure’. If the recent claims of President Putin have to be believed, the Russian Avanguard HGV is capable of flying at Mach 20-27 (24696-33,340 kmph) or the Chinese Starry Sky 2 HCM is capable of flying at 5.5 to 6.5 Mach3.
  3. At the above speeds, there is no way any conventional air defence or missile defence system in whatever state of readiness it may be in, can ever hope to even get such a target on its sensors, forget about tracking it or killing it by launching any air defence weapons, be it aircraft , missiles or guns.
  4. Such weapons are therefore claimed to be un-stoppable and the conventional air defence battle chain as described above,is redundant and useless in countering this threat.
The Drone Swarms

The second type of weapons which are capable of making conventional air defence battle sequence redundant are the swarming drones. Why?

  1. The biggest strength of the drone swarmslies in their sheer numbers. Much like the locust swarms which can eat thousands of square hectares of standing crop in a matter of minutes, while every single weapon in the armoury of the humans can only look helplessly, swarm drone present the same fait accompli.
  2. https://www.google.co.in/search?q=swarm+drone+the+future+of+aerail+warfare&tbm

  3. The conventional air defence systems based on the trio of ‘sensors’, (radars, electro-optical systems etc) ‘shooters’ (aircrafts, guns, missiles etc.) and battle management systems are limited by ‘finite capabilities’.
  4. By that it is implied that every sensor has a peak limit of how many targets it can track at a time and every shooter has a limit on the maximum number of targets it can possible engage at one time. What if that limit is beaten by a count of hundred or thousand? Conventional stems will simply collapse.

    An apt simile could be a few persons trying to stop a running stream of water by putting their hands in the flow of water as barriers. However hard they may try, the water will simply flow past all around their hands. Swarms can just do that. Conventional air defence weapon systems prove to be redundant and toothless against drone swarms.

  5. Thanks to the enabling tools of Artificial Intelligence (AI), one other strength of drone swarms is their capability of ‘group think’ where each vehicle of the swarm perceives itself as a part of the total swarm grid. Consequently, any one or a couple of vehicles getting shot down has no effect on the swarm as the balance of vehicle re-adjust to make up for the loss and the swarm continues to push ahead resolutely in completion of its assigned mission. Much like thousands of inspired warriors coming in like a wave-front and undeterred by the fact that a few of their comrades have fallen to their adversary!
  6. Another capability of the swarm is their ability to take independent decisions (based on a pre-fed AI logic) where, either there are no orders or there is lack of clarity in the same. Swarms can avoid known air defence weapon concentrations and choose the best route to their target. These can move precisely through enclosed spaces, galleries, bottlenecks, doors, windows and pick and choose targets to be killed.
  7. https://www.google.co.in/search?q=intelligent+swarm+drones&tbm

  8. Against such AI warriors conventional air defence weapons firing dumb or at best guided weapons have no chance. Drone swarms will be unstoppable by them.
  9. If the defenders do the costly mistake of launching their SAMs in taking out swarms, the result will be a fiasco of killing a few hundred dollars with a few million. In any case, most of the swarm will go past while the SAMs will take out a few; that too at prohibitive costs!
Dealing with the Swarm Threat

The challenge can be broken down into two problem statements:-

  1. How to detect the incoming drones?
  2. How to kill them?
Detection of Drone Swarms

Following points are made:-

  1. While, it has been stated earlier that each sensor, be it radar or an electro-optical device has a finite limit to ‘track’ the targets it has no limit for ‘detection’ of aerial targets, per se. The tracking implies that the device has ‘locked on’ to the target (the radar will continue to look at the target irrespective where it goes). Once the target is being tracked, the sensors get the capability of guiding air defence means (aircrafts, missiles, guns etc) towards the same. The detection on the other hand is simply painting on the radar screen airborne objects that are seen by the sensor device.
  2. The point being made here is that radars suitably placed will be able to pick up an ‘area target’ like a swarm of drones.
  3. The Saudi drone attack case is examined briefly in the context of the question; ‘was detection of the incoming drones possible?
    1. At the Saudi Oil facility that was hit by the drone strike in Sep 2019 there were two types of air defence weapons deployed for its protection, namely, the US MIM-104 Patriot SAM system and Oerlikon GDF 35mm twin towed anti-aircraft guns with Skyguard radar4.
    2. https://www.google.co.in/search?q=mim+104+patriot+missile+system&tbm

    3. Expert analysis revealed that the 18 drones and 7 cruise missiles that were fired executed an ultra-low-level flight profile that enabled them to remain just below the radar horizon hence remaining undetected all the way5.
    4. The problem therefore was not that the radars were incapable of detecting the incoming drones and cruise missiles but because the raiders adopted radar evasion tactics.
    5. Suppose the radars were suitably deployed so as to cover ultra-low level region just over the horizon( may be, deployed on elevated platforms or on a gradually rising ground even if that was to be artificially created in the desert) these would have not let the attack vehicles go undetected.
    6. Skyguard radar though a 1970 design has seen many an upgrades over the years. Its version employed with GDF 35 mm, the radar operates in I/J/K band of frequencies (8-20 gigahertz or GHZ6). It has a range of 20 km and a resolution (capability to distinguish between two adjacent targets in range) is 160m7. It is felt that this sensor if deployed in adequate numbers and at correct places would not have let the raid go unnoticed.
    7. The fortunate thing with drone swarms is that unlike hypersonic attack vehicles which simply give no time to detect, the swarms are relatively slow moving aerial vehicles which by virtue of their numbers present a target, large enough in its radar cross-section (RCS) as to be detected by a modern day sensor, be it a radar or an electro-optical device.
    8. It is stated that a high-resolution radar preferably operating in ‘fire control bands’ (frequency bands where radar detects very precisely and can direct air defenceweapons on the threat), and suitably deployed as to cover the threat envelope which may be low (30-300m) or ultra- low ( <30 m), will in all probability, be able to detect incoming drone swarms. Such fire control bands are X (8-12 GHZ), Ku (12-18 GHZ), K (18-27 GHZ) and Ka (27-40 Ghz). A range of 18-25 kms and a range resolution of 150 m at 20 km areconsidered adequate.
    9. In addition to the radars, the Electro-Optical (EO) sensor systems (operating in the band, 30-3x1011Hz) complement the radar solution ideally. In that, if the radar is jammed or the radar cannot see the target for any reason whatsoever (target lies in the radar shadow/radar dead zone etc.-not explained further), the EO systems are likely to detect the target.
    10. The ground based surveillance provided by the integral early warning and fire control sensors of air defence weapons deployed at the assets, could be backed with airborne surveillance (through Airborne Warning and Control System or AWACS).
    11. In super-sensitive areas where the vulnerabilities being protected are national strategic and critical assets, the surveillance cover could be further reinforced with satellite-based surveillance in a ‘fixed gaze’ mode where the area over the asset is always in the surveillance pan of the satellite.

    That much for the surveillance and detection of the swarming drones which is very much a possibility.

    Killing a Drone Swarm?
    Conventional Weapons- a misfit

    To arrive at what will be suitable to kill a drone swarm, it is essential to rule out what is not. In that, the following air defence weapons will be unsuitable (read incapable) to take out a drone swarm:-

    1. Surface-to-air-missiles (SAMs) of any range and variety from very short, to short, to medium to long range. Not only the same will be a case of trying to hit a fly with a sledge hammer, the SAMs will be able to take out just a few of the swarm members; the ones which lie their warhead explosion zone (blast/fragmentation /heat /pyro etc). What about the balance of the swarm?

      Besides everything else, such an option will be highly cost-skewed in favour of the attacker. A case of killing a few hundred dollars with many million dollars!

    2. The aircrafts scrambled in the interception mode. Such a mode of attack will simply not be possible in a one-on-one aerial duel. Yes, if the swarm drone could be identified at a long range there may be a remote chance of using an aerial platform to carry out ‘area bombing’ with blast/fragmentation warhead provided collateral damage to own areas can be avoided.
    Suitable weapons to counter drone swarms

    Having mentioned the weapons ‘not suitable’, following are the type of weapons that are suitable:-

    Conventional Mode

    In the conventional mode, ground based air defence guns with rates of fire in the range of thousands of rounds-per-minute are capable of creating a ball of fire in a volume of space that is populated by a swarm drone. Keeping in mind that the density of the drones in a finite volume of space will be high there will be a good chance of debilitating large number of them. (For instance, M133 GAU- 17 Gatling gun has a rate of fire of 2000-6000 rounds per minute8)


    Unconventional Mode

    In the unconventional mode, the ideal weapons to counter the drone swarms are the ‘soft kill’ weapons. Such weapons target the swarms along the following vulnerabilities:-
    Attack the electronics on board the swarm vehicles in the following manner:-

    1. Using killer laser waves to impinge on the miniature drones.
    2. Carrying out an electronic attack to jam/disable/disrupt the tele-communication and/or satellite-communication links of the swarm with the operators in the rear.

    In various Defence Exhibitions/ Workshops and other such forums, anti swarm weapons have begun to make their appearance.
    Such anti drone systems today are typically employing dual solutions both for the detection of drones, as well as, for killing them. Following is the pattern:-

    1. A radar and an EO based dual sensor solution for detection of drones.
    2. A laser and an RF based dual kill solution to achieve the kill.

    A sample of some anti-drone solutions from various countries is presented:-


    Israel, which faces the perennial threat of rockets and missile attacks (often fired in swarms) from the Hezbollah, has been testing several soft-kill weapons to take on the threat.

    An Oct 2019 report from Israel stated that they have successfully tested a 5-10 KW laser weapon that could destroy drones upto 2.5 km9.
    Israel later built the Drone Dome system. This system is a counter UAS (c-UAS) system employing the dual surveillance and dual kill system as described above. It has a range 3.5 km for a target with RCS of .002 m2 10


    China has showcased its anti-drone system called Silent Hunter. It is a 30KW laser system effective against low flying drones in the range bracket of 200m-4000m.11


    In Nov 2019, the US company Lockheed Martin showedits laser based anti- drone system called Advanced Test High Energy Asset (ATHENA) 12. This system employed advanced beam control technologies in directing a fibre laser on to the drone threat. c-UAS capabilities were claimed to a range of 4-5 kms13.


    Russia in 2017 came out with REX 1 anti-drone system whose upgrade appeared in 2020 as REX-2. As late as in Feb 2020, it was reported that the REX manufacturer M/s Zala Aero has come out with an anti-drone hand gun14.

    https://www.google.co.in/search?q=Rex+2+anti-drone+hand+gun+Russia &tbm

    All the Above Systems will FALL SHORT

    While some anti-drone systemsas briefly mentioned above are claiming success in defeating the drone threat, all of them ( except may be the drone hand gun if deployed in large numbers) are likely to fail or at best will prove sub-optimal in dealing with swarm drone threat. Why so?
    All the above conventional laser systems are for killing a finite number of drones by tracking each one of them and directing killer laser beams on them. What if the drones present themselves in multiples of hundreds? How many the Drone Dome or Silent Hunter or ATHENA will kill? A very finite number which will prove to be miniscule when compared to the hundreds that are coming in for attack.

    A swarm drone kill system will require some different capabilities. What could be these?

    1. It must be an ‘area defence’ system.
    2. The killing/debilitating effect it produces must not be restricted to a threat vehicle or two; it must engulf the whole airspace being used by the swarm.
    3. The kill must be attempted on an umbilical cord controlling the entire swarm such as following:-
      1. The GPS/INS/4G/5G/LTE (long term evolution) link connecting the swarm with their operators.
      2. Mass jamming of swarm network.
      3. Mass frying up of swarm electronics and electromagnetics by an overwhelming laser/heat kill wave engulfing the entire threated air space. (Very tall order!).
    4. There is a need of going beyond laser and developing such area soft kill weapons that are based on ‘charged particle beams’ which come down as millions of charged ‘lightning bolts’ on the advancing swarms or the ‘high power microwave’ weapons that are capable of destroying the material integrity of the swarm body.
    5. It will be a hacker’s challenge to try and take-over the swarm command through a hacking/phishing attack. A distant dream as of now.

    These are the type of challenges which lie in the near future if swarm drone attacks are to be countered ‘effectively’ and ‘economically’.

    End Thoughts

    It is felt, that like all other matters between the ‘prosecutors’ of the air threat and ‘defenders’ therefrom, the matter of killing the swarm drone effectively will also besettled indue course following the eternal cause-effect cycle and true to the dictum – ‘To every sword a shield’.

    Where is India?
    1. Most of the details on the progress of laser based (and other) soft-kill weapons are in the classified domain. Suffice to say there is forward movement (privileged information not covered).
    2. As late as Jan 2020, a capability to kill hostile drones using radio frequency attacks, as well as, laser kill beams was reportedly deployed to guard VVIPs in a parade in India15.

    Drone killing? Fine. What about swarm killing???

    It is like the Corona virus. The vaccine is under development!
    End Notes
    1. “Drone swarms a growing lethality. Where is the world? Where are we?” at https://www.vifindia.org/article/2020/april/06/. Accessed on 06 Apr 2020.
    2. “Russia says January 5th attackon its Syrian airbase was by a swarm of drones,” at www.the drive.com.Accessed on 03 Apr 2020.
    3. “China conducts new hypersonic weapon test,” at www.popularmechanics.com.Accessed on 03 Apr 2020
    4. “Are air defence weapons ready to confront drone swarms,” at www.defencenews.com. Accessed on 03 Apr 2020.
    5. ibid.Accessed on 03 Apr 2020.
    6. “Radar frequencies” at www.copradar.com.Accessed on 03 Apr 2020.
    7. ‘Skyguard” at www.forecastinternational.com.Accessed on 03 Apr 2020.
    8. “M134 GAU-17 Gattling gun,” at www.military.com.Accessed on 04 Apr 2020.
    9. “Are Air defence systems ready to confront Drone swarms?”at www.defensenews.com.Accessed on 04 Apr 2020.
    10. “Drone Dome c-UAS system,” at www.rafael.co.il.Accessed on 04 Apr 2020.
    11. “IDEX 2019” Chinese company Poly defence displays silent hunter laser defence system,” at www.armyrecognition.vom.Accessed on 05 Apr 2020.
    12. “Counter drone laser weapon demonstrated,” at www.unmannedsystemstechnology.co.Accessed on 05 Apr 2020.
    13. “ATHENA successfully defends drone threat,” at www.news.lockheedmartin.com.Accessed on 05 Apr 2020.
    14. “Meet the REX 1: Russia’s new anti-drone hand gun,” at www.nationalinterest.org. Accessed on 05 Apr 2020.
    15. “Anti-drone tech used for the first time to guard VVIPs at parade..” at www.m.hindustantimes.com.Accessed on 05 Apr 2020.

    (The paper is the author’s individual scholastic articulation. The author certifies that the article/paper is original in content, unpublished and it has not been submitted for publication/web upload elsewhere, and that the facts and figures quoted are duly referenced, as needed, and are believed to be correct). (The paper does not necessarily represent the organisational stance... More >>

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