Loitering munitions may be increasingly morally questionable, but their effectiveness is undeniable.
The use of loitering munitions during the 2020 Nagorno-Karabakh war, during Russia’s intervention in Syria, and now in Ukraine, have brought this emerging technology into the limelight, demonstrating their potential on the modern battlefield, and highlighting some of the issues surrounding their use.
Loitering munitions are not a new concept, however, dating back to the 1980s, when a number of loitering weapons were developed for use in the suppression of enemy air defences (SEAD) role. Their ability to persist in the target area provided a simple solution to the problem of a target emitter simply being ‘switched off’ to defeat conventional anti-radiation missiles, since they could wait for the radar to be ‘switched back on’ and then attack. The IAI Harpy was the classic example of these first-generation loitering munitions. Usually transported and launched from a truck-mounted canister, the Harpy is a ‘fire-and-forget’ weapon programmed before launch to fly to a pre-defined area, where it then loiters and searches for hostile air-defence radars to attack.
Even before the Nagorno-Karabakh War, some analysts were enthusiastic about the potential of this class of weapon, describing loitering munitions as ‘a form of unmanned system that will impact the character of warfare more substantially than the introduction of the machine gun did at the turn of the last century.’
The term ‘loitering munition’ today covers a wide range ofAmaliaweapons, with very different characteristics and roles, and produced at very different ‘price points’. Some employ a man in the loop, while others are pre-programmed and a few incorporate some measure of autonomy. All are indirect fire weapons, designed to engage a target without relying on a direct line of sight between the launcher and its target, allowing targets to be engaged even if they are behind cover. Such systems are able to ‘loiter’ or persist in the target area to engage fleeting or emerging targets, able to receive real-time target information from a range of sources, and able to follow an unpredictable course rather than following a set trajectory like a mortar or artillery round.
Some have compared loitering munitions to airborne landmines, placed into an environment where they are then responsive to characteristics they can detect with their onboard sensors. But this is simplistic, and minimises the military value of this class of weapon. Loitering munitions enable faster reaction times against concealed or hidden time-sensitive targets that may emerge for short periods, and they can be recalled or aborted right up until the final strike, and they do so without needing to place or maintain higher-value carrier platforms close to the target area.
Close Fight
The smallest loitering munitions are designed for the ‘close fight’, providing company or even platoon leaders with an expendable organic strike system capable of precision attacks at beyond-line-of-sight, man-portable and cheap enough to be dispersed around the battlefield with small units and expended at the same kind of rate as mortar or artillery rounds. This kind of loitering munition typically requires only a small anti-personnel warhead or, at most, a warhead capable of disabling a lightly armoured vehicle. They will generally have a range of at least five miles (eight kilometres), and a loitering endurance of 15-45 minutes.
Loitering munitions designed to support the close fight are proliferating globally, and include the class-leading, US-made AeroVironment Switchblade 300, the DefendTex Drone 40, the Elbit Lanius, the IAI Rotem, the Turkish STM Kargu and Alpagu, the Polish WB Electronics Warmate, the UAE’s ADASI QX-1, and the Indian EEL Nagastra-1.
The next step on the capability ladder is provided by larger, longer range loitering munitions that may be used against more critical targets in support of a wider campaign, and that give battalions and brigades the kind of capability that is normally provided by modern rocket artillery systems and that are generally reserved for a division or a corps. These systems need a longer loitering endurance – of perhaps 1-3 hours – allowing them to engage critical enemy assets as they unmask. They will also tend to have a longer range, upward of 50 miles (80km). Systems like these have to be capable of destroying almost any battlefield target, and so require robust anti-armour capabilities.
These systems can allow a relatively small, dismounted team to perform some of the tasks of artillery, launching long-range attacks and disrupting operations across an entire theatre by finding and destroying headquarters, resupply convoys, and fuel dumps, and tanks ‘dug in’ in defensive positions, and not just those exposed during manoeuvre operations. In some respects, loitering munitions challenges longstanding assumptions about the survivability of armoured vehicles, and raises questions about their primacy on a modern battlefield.
The Aerovironment Switchblade 600 is typical of this class of munition. Heavier than the Switchblade 300, it is still man portable, but has a 25 miles (40km) range and a loiter time of over 40 minutes. And it has a warhead capable of killing tanks.
High End, Long Loiter
The most high-end loitering munitions have loiter times of 6-12 hours and ranges in excess of 100 miles (160KM) These systems are typified by the Israeli Harpy and Harop, and they are generally used to ‘shape the battlefield’.
In 2020, Azerbaijan’s Harop loitering munitions played a significant role in overwhelming the Armenian military, providing a persistent air threat to Armenian forces with its nine-hour endurance and anti-armour capability. Azerbaijan used its Harops to destroy Armenian air defences and then to attack other heavy equipment, including tanks, with relative impunity.
Cheap enough to be attritable, and usable without risking of costing the lives of expensively trained aircrew, these more exquisite loitering munitions represent an alternative to traditional tactical air power, and can effectively deny the enemy his use of operationally essential terrain.
Unlike traditional unmanned aerial vehicles (UAVs), these kinds of loitering munition are optimised to make quiet, high speed, high angle diving attacks, with forward facing cameras for targeting, and are designed to be single-use, expendable weapons.
These high end loitering munitions, can fulfil a dual purpose as reconnaissance platforms, using their sensors to relay target information back to the operator, and may be sufficiently valuable for recovery options to be considered (usually using a parachute) if they are not expended in an attack.
Not all loitering munitions are aimed at surface targets. In recent years a number of systems have emerged whose primary purpose is to target other unmanned aerial systems. These ‘drone killers’ include Raytheon’s Coyote, and the Transvaro-Havelsan Fedai.
Return of the Killer Robot
Loitering munitions can hunt for a target under human control, or increasingly may fly autonomously, with authority to strike designated targets or target types, or with a man-in-the-loop giving ‘consent’ for weapons employment.
Direct human control may not be necessary, or even desirable, since these weapons are designed to operate in challenging battlefield conditions, including GPS-denied environments and in the face of impaired or jammed communications. Instead, they may be programmed to fly around a defined search area autonomously highlighting potential targets to the operator. Once an attack has been consented to, the weapon itself can use AI to select the best attack direction, angle of impact, and timing. It may even be able to select the best target from a group – though this may be getting close to the point at which ethical concerns about the limits of autonomy start to become an issue.
But ethics aside, there is no reason why a loitering munition can’t search for and find an enemy convoy at a safe standoff distance, and then decide whether to hit the lead resupply vehicle or another vehicle, and whether to hit it before it reaches a bridge, as it crosses the bridge or after crossing the bridge.
A Question of Ethics
For decades, loitering munitions have been at the very outer edge of ‘acceptable/permissible levels of autonomous lethality’. While they were primarily targeted against air defence radars, this didn’t matter much, but as they are increasingly being used to target humans (whether soldiers or insurgents) they are increasingly raising moral and ethical concerns, and could even be seen as having the potential to violate international humanitarian law.
Loitering munitions that are capable of making autonomous, ‘man out of the loop’ attack decisions are particularly problematic, because no human being is involved in making the actual decision to attack and potentially kill other humans. Many missiles can be locked on after launch or may be sensor fuzed, but they tend to have a very limited flight time, and will only be launched where enemy activity is underway, whereas an autonomous loitering munition may be launched at an area where enemy activity is only probable, and will then loiter (potentially for hours) searching autonomously for targets. Many believe that such weapons should be subject to the same sanction as landmines that cannot discriminate between legal military combatants and innocent civilians.
Some have called for moratoria or limits on use, while others have called for direct human input into targeting and consent for attack, effectively making autonomous weapons subject to human supervision. It has been argued that this would undermine the military utility of these weapons, especially in GPS-denied or communication-degraded environments.
It should come as no surprise that both sides have made extensive use of loitering missions in the war in Ukraine.
Russia’s autonomous Lancet, made by Kalashnikov subsidiary the ZALA Aero Group was used in Syria in 2021 by Russian special operations forces, and the latest Lancet-3M variant is claimed to have destroyed 10 towed artillery guns, seven self-propelled guns, six surface-to-air missile launchers, four radar vehicles, and a radio relay station used to control Bayraktar TB2 drones, together with six hits on tanks and eight on armoured personnel carriers and other light armoured vehicles.
Russia has also been using the ZALA KYB munition, but this has reportedly enjoyed little success, some failing to detonate and others being brought down by Ukrainian air defence systems or by electronic warfare systems.
Ukraine has been supplied with large numbers of AeroVironment Switchblade 300 systems, (each consisting of a handheld ground control station, a launcher, and several Switchblade air vehicles) with at least 700 delivered. The US Department of Defense (DoD) then procured the larger Switchblade 600 system for Ukraine. This incorporates an anti-armour warhead for use against larger, hardened targets. The US government has also supplied the Phoenix Ghost family of systems which are reportedly similar to the Switchblade system but with a longer endurance of more than six hours and effective against medium armoured vehicles, which it can target by day or night using infrared sensors.
Ukraine has also developed and deployed its own loitering munitions, including the electrically powered, catapault-launched CDET RAM II, and the UAV-launched Athlon Avia ST-35 Silent Thunder.
SHAHEDS In Ukraine
The most prominent loitering munitions used in Ukraine have been the Iranian-built Shahed-131 and 136 UAVs supplied to Russia and named Geran 1 and 2 in Russian service, though these delta-wing missiles rely primarily on GNSS or GPS satellite-based navigation systems to attack specific geographic co-ordinates, and do not loiter while searching for targets using their own onboard sensors. This means that they are effective only against pre-selected stationary targets and act as ‘kamikaze’ drones and not as true loitering munitions. The Shaheds seem to have been used principally against civilian targets and particularly against Ukraine’s electricity infrastructure. There is some evidence that Russia has started to employ these weapons in tandem with Mohajer-6 ‘spotting drones’ operating as an integrated reconnaissance-strike complex. The ‘spotter’ relays target co-ordinates to the Shahed or to a centralised UAV command unit, reducing the delay between target identification and engagement and allowing the Shaheds to be used against mobile or even moving targets. It is unlikely that Russia has the capacity to establish these procedures widely or routinely, or to regularly deploy UAVs and loitering munitions together in the near term, at least.
The military utility of loitering munitions, as demonstrated in Nagorno-Karabakh and now Ukraine seems likely to stimulate demand for these systems, though a growing public distaste for autonomous unmanned systems (‘killer robots’) accompanied by questions and concerns about the morality of their use could still blunt this demand. The performance of these systems on a modern battlefield, in the face of heavy countermeasures and denied communications, remains to be fully assessed.
by Jon Lake
