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By Nicholas Drummond

Graphic images of Armenian T-72s being obliterated by Azerbaijani loitering munitions or “kamikaze drones,” as the media prefer to call them, suggest that the modern battlefield has become unsurvivable for heavy armour. Does this mean that we should retire our tanks and infantry fighting vehicles? This article considers the implications of loitering munitions not only for tanks, but for contemporary combined arms manoeuvre warfare doctrine in general. 

Azerbaijani Harpy Loitering munition being launched (Image: Azaerbaijan Armed Forces)


01 What are loitering munitions?

02 Milestones in the development of loitering munitions

03 How can armies respond to the threat posed by loitering munitions?

04 Countering loitering munition launchers at source

05 Conclusion

Loitering munitions above Nagorno-Karabakh (Image: Azerbaijan Armed Forces)

01 What are loitering munitions?

Loitering munitions are a new category of highly sophisticated weapon created by the convergence of UAVs with precision guided weapons. Frequently described as low-cost mini cruise missiles, a price tag of around $100K hardly makes them cheap. However, compared to the $900K cost of Tomahawk Land Attack Missile (TLAM) or $12 million for a new Main Battle Tank, the economics of loitering munitions are compelling, especially as a single missile can reliably neutralise targets at significant stand-off distances. 

Targets can be predetermined by sending coordinates to the loitering munition in flight via a data link, in which case the missile functions autonomously. Alternatively, it can be piloted remotely by a human operator using a tablet computer that presents a view of the battlespace and target opportunities via onboard electro-optical and infrared cameras. Loitering munitions are relatively easy to control and can patrol the skies above the battlefield looking for targets. With an endurance of several hours, they can dominate huge areas of ground. If they fail to find a target, they can be recovered and re-used, which adds to their financial attractiveness. Even without engaging a target, loitering munitions are invaluable ISTAR assets. Their sensors gather battlefield data to facilitate informed decision-making and more efficient command and control. They also come with a reduced training burden, because operators can be taught to pilot them using simulators. This means fewer missiles need to be fired during peacetime training, reducing total costs. 

IAI Harpy Loitering Munition (Image: IAI)

Mounted on light vehicles, e.g. JLTV or Foxhound LPPV, in pods of 4-8 missiles, loitering munitions can be deployed quickly. Newer, more compact systems can also be carried by dismounted infantry. Varying size warheads allow a range of targets to be engaged, including tanks, armoured vehicles, buildings, bunkers, and dug-in troops. A critical advantage is pinpoint accuracy, allowing enemies to be neutralised with precision, speed and certainty, but without incurring collateral damage. This makes loitering munitions invaluable for counter-insurgency missions, as well as for high-intensity peer-to-peer warfare. 

Launch vehicles can be located well back and beyond the line-of-sight of approaching enemy forces. The missiles themselves have a reduced signature in flight versus conventional UAVs, making them difficult to spot until they commence an attack. Picking-up speed as they dive towards a target, they emit a shrieking, siren-like noise not unlike the Stuka JU-87 dive bomber of WW2 fame, which gives them a psychological effect. As newer designs fly higher and faster than before, those on the receiving end have less time to take evasive action. The ability to engage multiple targets simultaneously and without warning offers a decisive advantage across multiple scenarios.

UVision Hero 400EC mounted on JLTV is an extremely compact and mobile loitering munition system. It has a 40 km range, weighs 40 kg, with a 10 kg shed charge warhead, and has a two-hour endurance. (Image: Defence Blog)

In defensive situations, loitering munitions can bring an armoured assault to a standstill. Remotely guided by operators positioned many kilometres to the rear or in forward positions, launch vehicles can only be detected by their electro-magnetic signature. Without EW / ECM capabilities, it is very hard for an armoured column to respond to an enemy it cannot see. This makes loitering munitions ideal for holding ground. They can also support attacks by providing an assault gun-type of capability to neutralise bunkers or dug-in infantry. 

The use of loitering munitions during the Nagorno-Karabakh conflict was widely recorded by Azerbaijani drones and posted on social media. According to Dutch warfare research group Oryx, which documented visually confirmed losses on both sides, Armenia lost 222 tanks, 58 other armoured vehicles, plus 540 trucks and jeeps. Meanwhile, Azerbaijan lost 36 tanks, 14 other armoured vehicles, and just 31 trucks and jeeps. The role of loitering munitions in inflicting significant Armenian casualties was cited by UK Defence Secretary, Ben Wallace MP, as ample evidence of their transformational impact and recognition that they are an essential addition to any land force’s future toolbox. 

Summary Loitering Munition Advantages

  • Low cost
  • Portable / rapidly deployable
  • Easy to operate
  • Flexible 
  • Relevant to high intensity warfare and counter-insurgency operations
  • Precision
  • Lethality
  • Able to be used across all phases of battle (Attack, Defence, Withdrawal & Advance)
  • Mission abort function to avoid collateral damage

02 Milestones in the development of loitering munitions

The first proper loitering munition to be fielded is generally considered to be the Israeli IAI Harpy. Developed during the 1990s, this has a 200-kilometre range, a nine-hour endurance, and carries a 16 kilogram warhead. (A 155 mm shell typically has a 10 kilograms of explosive.) This type of missile was originally conceived as an anti-radar weapon with sensors that homed-in on the signals emitted by ground-based air defence systems. It didn’t take long for users to realise that Harpy had a wider utility. Potential adversaries were quick to see the potential of loitering munitions as anti-structure and anti-tank weapons. Somewhat controversially, Harpy was sold to China which has since developed in its own range of loitering munition by replicating the same technology. Russia has developed its own family of loitering munitions, ZALA, which has been used successfully in Syria and which it continues to refine. 

In 2004, IAI released the Harpy 2, now re-named Harop. This offers the same performance as Harpy in a smaller, more robust airframe. Turkey was the launch customer, followed by India. Harpy has been sold widely and is the loitering munition that was used to great effect by Azerbaijan during the Nagorno-Karabakh conflict. Harpy was offered to the UK by MBDA as the White Hawk as part of a 2004 evaluation of off-the-shelf loitering munition systems. When none of the demonstrated options was considered to meet British Army requirements, MBDA was commissioned to develop Fire Shadow. This was a larger, 500-kilogram loitering munition with a 100 km range and a six-hour loiter time. Initial prototypes were delivered, but the programme never went beyond an early development stage. It is surprising that the UK has been so slow to field a loitering munition system, but the category has evolved quickly with new systems offering longer ranges in smaller packages. Over the last decade, newer loitering munition designs have benefited from better flight characteristics, improved software, simplified operator controls, and miniaturised electronics. They now offer day and night, all-weather performance, have a smaller radar signature (making them harder to detect) in more compact designs at a lower price. IAI’s Mini Harpy weighs just 40 kilograms, yet has a 100-kilometre range, a 2-hour loiter time, and carries an 8-kilogram warhead. 

The USA has naturally jumped on loitering munition bandwagon. The Switchblade family of expendable, tube-launched UAVs was conceived as a means of increasing the firepower of dismounted infantry units on the ground. Development by AeroVironment, the latest Switchblade 600 is a compact, man-portable system that weighs 23 kilograms, has an 80-kilometre range and 40-minute loiter time. Equipped with high-resolution gimbal-mounted sensors and enhanced flight control software, it can fly, track and engage beyond-line-of-sight targets without the need for external ISR support.

Switchblade 600 tube-launched expendable UAV, loitering munition (Image: AeroVironment)

Another Israeli company, Uvision, has developed what is effectively a third-generation loitering munition family with nine different products varying in size, range and payload.  One of its latest and most sophisticated options is the Hero 400EC. This has an advanced electro-optical / infra-red (EO/IR) guidance system with high resolution cameras. It can locate, track and strike static and moving targets. It also has a mission abort function, which is useful for avoiding collateral damage after an attack has been initiated. With a 40-kilogram missile, a 10-kilogram warhead, a 150-kilometre range, and two-hour endurance, it sets a new benchmark for the category. 

The Uvision Hero 400EC sets a new performance benchmark in the 40 kg category. Benefitting from improved flight control software and high fidelity sensors, its offers exceptional precision and reliability. (Image: Uvision)

One other system that deserves a brief mention is Rafael’s recently announced Spike Firefly. This is a small three-kilogram, short-range rotorcraft UAV with an explosive payload of 0.35 kilograms, and a range of one kilometre. With contra-rotating blades, it is very easy to pilot, and maximises control and accuracy in urban environments. This makes it suitable for neutralising enemies in defilade positions. Increasingly, loitering munitions are positioned as infantry weapons because their increasingly compact dimensions make them an effective alternative to rockets and mortars.

While most existing loitering munition systems were conceived as land-based weapons, many lend themselves for use at sea and provide warships with eyes and ears as well as a beyond-visual-range offensive capability. The more recoverable unused missiles can become, the wider their maritime appeal will be.

As the loitering munitions category continues to evolve and mature, a further convergence is taking place. Mid-size loitering munitions are very similar in concept to NLOS anti-tank guided weapons, such as Spike NLOS, and other mini-cruise missiles, like Brimstone 2 and Spear. The category is expected to mature further with different systems offering short, medium, and long range / endurance capabilities as well as different payload / warhead options. Finally, very small autonomous loitering munitions can be used as the basis for drone swarms. With autonomous guidance and AI systems programmed to recognise specific targets, these can be used to neutralise concentrations of infantry in the open, while larger drones can be swarmed for attacks against armour. The potential of drone swarms is driving factor behind the dispersal of units on the ground.

A recent summary of loitering munitions in service can be found here.

03 How should armies respond to the threat posed by loitering munitions?

Many within the defence community have suggested that the proliferation of loitering munitions will make heavy armour redundant. The economics of a $100K dollar missile versus a $10 million tank certainly seem to weigh heavily in favour of loitering munitions. Given that tanks can also be targeted by a wide array of handheld rocket-propelled grenades (RPGs) and anti-tank guided missiles (ATGMs), the investment in costly MBTs and IFVs seems increasingly difficult to justify. 

Armenian T-62 MBT destroyed by a loitering munition in Nagorno-Karabakh. (Image: Azerbaijan Armed Forces)

However, the proposition that loitering munitions make tanks obsolete is fallacious. The effectiveness of loitering munitions should not be used to argue against having heavy armour, but for increasing / enhancing the protection such vehicles offer. If we stop using tanks and armoured infantry carriers, our enemies will no longer need missiles that cost $100K to defeat us; they will be able to win using bullets that cost a mere ¢50. We are still better off with vehicles that offer protection than we would be without them. 

The challenge is to protect armoured vehicles against loitering munitions. This is not as difficult as it may seem. Active protection systems (APS) fitted to main battle tanks can already reliably defeat ATGMs. The success Israel has achieved fitting the Trophy APS to its Merkava IV MBT has restored its battlefield primacy. Once again, it can move with near impunity. If you want to defeat an Israeli tank, you will likely need another tank that fires APFSDS ammunition, although even the effect of long rod penetrators has also been diminished by APS.

As armies begin to recognise the importance of countering loitering munitions, tank and infantry carrier survivability will depend on the wider adoption of more sophisticated APS systems that are further able to engage aerial targets. Development of such systems is the current focus of many defence firms. APS can protect a vehicle in two ways. Firstly, through “hard kill” systems that physically engage and defeat a threat; and, secondly, through “soft kill” systems that interrupt or spoof a missile’s electronic guidance system, causing it to fall harmlessly out of the sky. 

APS are linked to active electronically scanned arrays (AESA) radars. These have computer-controlled phased array antennae, which project a beam of radio waves in different directions without the need for a rotating scanner. This makes them smaller, lighter and more compact for use in armoured vehicles. Additionally, laser warning systems are fitted and these can detect missile lock. There is no reason while the protection offered by existing APS systems cannot be extended to create an invisible  360o domed shield around a vehicle. The radar tracks an incoming loitering munition before triggering a defensive munition that neutralises it, usually within one kilometre of the vehicle. 

US Army Mi1A2C Abrams MBT fitted with Rafael’s Trophy Active Protection System (APS). Note the oval shaped plates on the left and right side of the turret. These are AESA radar units used to locate incoming ATGM threats. The tank also now has a remote weapon station. (Image: US Army)

A second “Hard kill” option is to improve the weapons fitted to remote weapon stations. Existing RWS are evolving so that they combine cannons and missiles, with both weapon types able to engage aerial or land-based targets. Various firms, including Rafael, Kongsberg, SAAB, and Rheinmetall, have started to develop weapon stations capable of  destroying drones and loitering munitions, as well as regular ATGMs.

Most of NATO needs to invest in air defence capabilities. Although VSHORAD missiles like Starstreak HVM and Stinger remain highly effective, using $100K missiles to defeat low cost drones is inefficient, if not unaffordable. While man-portable air defence systems (MANPADS) can certainly be used to counter loitering munitions, a lack of sufficient launchers across a brigade combat team means that it may not be possible to provide total coverage against potential threats. Consequently, air defence cannons are needed as a back-up solution. These can also be used to defeat smaller low-cost drones.

Vehicle cannons can be expected to become dual-role weapons able to support infantry against ground targets, but also to offer utility against aerial targets including drones, UAVs and loitering munitions. Existing cannon types firing new programmable airburst ammunition are potent weapons, especially when linked to air defence radars, e.g. SAAB Giraffe 1a. Advanced C4I /BMA systems can also connect sensors to effectors, so that even weapons without organic sensors can be fed aerial target coordinates from nearby radar systems. One problem that needs to be addressed is the slower rate-of-fire of current vehicle cannons (circa 200 rounds per minute). Faster-firing cannons (600-1,000 rounds per minute) are needed, but these are ammunition hungry. This makes more lethal air burst ammunition a priority. 

Northrop Grumman is developing an airburst ammunition nature for its 30×113 mm M230LF chain gun. This cannon attached to a remote weapon station, such Kongsberg’s RS6, or MOOG’s RiWP, is an effective air defence solution, and has been incorporated in the US Army’s new Stryker M-SHORAD system. The US Marine Corps’  MADIS program will add a mix of 7.62×51 mm M134 Miniguns, 30×113 mm M230LF chain guns, and Stinger MANPADS to its fleet of JLTVs. Guided by radar these vehicles will offer a formidable counter-UAS / loitering munition capability. 

US Marine Corps JLTV fitted with MADIS program air defence system. This vehicle has a Kongsberg RS4 RWS mounting an M134 7.62 mm Minigun. Behind this is a multi-directional AESA radar array and an electro-optical / Infrared sensor above it. A second vehicle mounts the Northrop Grumman XM914 30 mm chain gun. (Image: USMC)

Northrop Grumman is also developing a new cannon for the US Army’s Future Attack & Reconnaissance Helicopter (FARA) program, the 20×102 mm Sky Viper chain gun. This will also have an airburst ammunition nature, but, critically, it’s a higher velocity weapon with rate of fire three times that of the 30×13 mm M230LF. So, it will likely be more accurate and more capable of defeating high speed aerial targets. Meanwhile, the Bushmaster 30×173 mm chain gun and the Rheinmetall / Oerlikon SkyRanger 35×228 mm cannon, already offer exceptional air burst ammunition solutions.

Northrop Grumman 20×102 mm Sky Viper cannon. This is being developed for the US Army’s Future Attack & Reconnaissance Helicopter (FARA) Program. Unlike the M230LF 30×113 mm cannon, Sky Viper has a much higher rate of fire (625 rpm versus 200 rpm) and shoots at a much high velocity. Combined with a new airburst ammunition, this is likely to offer an extremely effective counter UAV / loitering munition capability in a lightweight, low-cost RWS. (Image: Northrop Grumman)

In terms of “Soft kill” APS solutions. The ability to confuse or jam missile guidance systems is already quite mature. However, interrupting a data connection to a loitering munition in flight is likely to be difficult for individual vehicles until the threat is very close, by which time it may be too late. Consequently, longer-range soft kills may require something like a high energy laser. These are still immature, but technology in this space is advancing quickly. A better approach to “soft kill” systems may be offensive EW from forward deployed reconnaissance units tasked with searching for loitering munition launchers. 

Used in conjunction, the above systems have the potential to create a layered counter-UAV, counter-loitering munitions solution:

  • Soft kill EW is used to find, track and jam missiles as soon as they are identified. 
  • Air defence cannons and missiles are than used to engage them, ideally before they commence an attack
  • Finally, APS provides a last ditch defence in case the missile gets through. 

04 Countering loitering munition launchers at source 

Light vehicles used as loitering munition launchers are easy to conceal. But once a loitering munition has been fired, the active data link between the crew and the missile in flight as it patrols an area will emit a significant electromagnetic signature. If we can block or jam the GPS signal, the loitering munition is likely to crash without causing any damage. We can also identify the source of the signal and attack this. 

An important means of countering both UAVs and loitering munitions is to use our own UAVs flying above an advancing formation on the ground to provide counter-loitering munitions support. Equipped with air-to-air missiles and ECM pods, UAVs can be used to neutralise loitering munitions in flight. They can also be used to locate the source of a GPS signal on the ground and to attack launch vehicles in situ with missiles like Brimstone. 

We should not underestimate the importance of EMCON (emissions control) when using our own loitering munitions to prevent both missile and launcher from being targeted. As soon as voice and data communications or navigational equipment is used, it becomes visible electronically. Enemies using loitering munitions without disciplined C4I will be rapidly neutralised. This makes our own offensive EW capabilities more important than ever. 

While our own UAVs in the air and EW resources on the ground will be important counter-measures, we will also need to operated dispersed to create fewer targeting opportunities. This is important to protect against rocket and tube artillery too. As friendly forces advance, they will be more reliant forward deployed reconnaissance screens. These will operate much further forward than hitherto, blending-in with local population, and using small, highly mobile modes of transport, e.g. highly motorbikes and tactical golf carts. Locating loitering munitions launchers and other artillery systems is likely to become a Ranger Regiment task. It will be reconnaissance by stealth rather than using vehicles like Ajax. Equipped with EW systems, such troops may use friendly forces loitering munitions to counter enemy ones. When British Chief of the Defence Staff, General Sir Mark Carleton-Smith recently described future land warfare as a process of hiding and finding, he was undoubtedly referring to the implication of the widespread use of loitering munitions.

Special Forces in lightweight 4×4 vehicles operating well forward of friendly forces can be used to provide a means of hunting loitering munition launchers. Lightweight EM signature detection equipment can help to triangulate enemy positions based on their EM signature. (Image: Polaris)

05 Conclusion

Loitering munitions are a highly effective stand-off capability. They allow enemy forces to be targeted with surprise, precision and decisive lethality. Their ability to destroy enemy assets at relatively low cost makes them a force multiplier, enabling smaller forces can compensate for a lack of mass and prevail against more substantial peer adversaries. While loitering munitions are a relatively new phenomena in modern warfare, they preface a new age of precision guided weapons. It is obvious that the British Army and other members of NATO will need to adopt them more widely, but equally we must to field corresponding capabilities to counter them. The sheer number of aerial threats faced by troops on the ground means that ground-based air defence has become a much greater priority than it has been at any time since the Cold War. 

We can expect NATO armies to re-equip their SHORAD artillery regiments with systems that offer a combination of cannons and missiles linked to capable radar systems. But these are expensive and we are unlikely to be able to afford the number of systems we need for universal coverage. This means that active protection systems for armoured vehicles will be essential too. As well as protecting vehicles from ATGM threats, these must also be capable of countering aerial threats in the same way that naval CIWS protect warships. To improve vehicle-mounted APS systems, these will need to be linked to improved radars, EO/ IR sensors, and remote weapon stations that mount light cannons, ATGMs and light air defence missiles. 

US Army Stryker M-SHORAD system. This uses a MOOG RIWP remote weapon station with an XM914 30×113 mm chain gun, a quadruple Stringer surface-to-air missile pod and twin Hellfire missiles. Like the US marine Corps JLTV-based system this has AESA radars and electro-optical / infrared sensors. (Image: US Army)

We will also need an offensive UAV capability with drones able to destroy loitering munitions in the air either through direct fire weapons (machine guns or air-to-air missiles) or through EM / EW capabilities that jam or block command signals from reaching munitions in flight. In future, high energy lasers could be used. 

We will use Special Forces as dedicated hunter-killer reconnaissance forces on the ground. Their job it will be to seek and destroy loitering munition launchers. Such forces will rely on EM / EW sensors to home-in on the electromagnetic signature emitted by enemy loitering munition launch vehicles. Finally, we can expect to use our own loitering munitions to counter enemy systems. 

If armoured vehicles are able to defend themselves against loitering munition and ATGM threats, they will regain freedom of movement around the battlespace, notwithstanding the threat of rocket and tube artillery. Traditionally, land warfare has been concerned about seizing and holding ground. But we may see an evolution where this can only achieved by first eliminating or degrading forces operating within contested territory. 

Loitering munitions are part of an ongoing “Revolution in Military Affairs.” The evolution of commercial technology and its military application, particularly through more compact and more lethal weapon systems and better communication systems has the potential to change doctrine a much as Blitzkrieg did in 1939. Azerbaijan was able to harness the power of loitering munitions successfully in Nagorno-Karabakh. It claims to have destroyed $2 billion worth of Armenian military equipment. While such losses are unsustainable economically, they cannot be replaced quickly. While the dispute over who owns Nagorno-Karabakh territory may not have been resolved, trying to do so militarily may come at too great a cost. As NATO armies continue to model the operational usage of loitering munitions, tacticians will undoubtedly invent novel ways to employ them, but only a real conflict will validate the ideal CONEMP. What is certain is that contemporary warfare has become much more dangerous and lethal. 

Ultimately, all MBTs, IFVs and armoured infantry carriers will need some kind of remote weapon station fitted with weapons and sensors capable of engaging aerial targets. Here an M134 7.62 mm Minigun on a Kongsberg RS4 can provide a significant close-in defensive effect. (Image: US Marine Corps)

When anti-tank missiles were used widely during the Arab-Israeli Yom Kippur of 1973, defence analysts started to write obituaries for heavy armour. In Iraq 1991 and again in 2002, heavy armour was an essential means of achieving a military victory. Combined arms manoeuvre remains relevant even though new weapon systems offer new attack possibilities. While we may need to configure our armies around novel weapons, armoured vehicles that balance firepower, with protection and mobility will still be needed to maximise survivability. The iron triangle may need to rebalanced in favour of a larger quantity of smaller protected vehicles, like JLTV, instead of a small number of extremely expensive MBTs and IFVs. However, we will still need to physically assault contested ground and nothing else offers the shock effect, potency and resilience of a 60-tonne battle tank.  

Finally, we need to remember that loitering munitions can only stay in the air for a few hours at a time. In other words, they are not persistent, whereas an armoured vehicle is. While loitering munitions can help a defending force to inflict severe damage on an attacking force, they cannot physically hold ground. Survival may boil down to infantry with rifles and bayonets digging trenches with overhead cover. 

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