Loitering munitions have been used in combat for more than a decade, but have only recently entered the limelight, most notably during the 2020 conflict between Azerbaijan and Armenia.
In Nagorno-Karabakh, loitering munitions emerged as a weapon of choice for strikes at the tactical and operational levels, due to their ability to provide a small force with persistent presence and rapid strike capabilities at relatively low risk. This trend continues somewhat in the War in Ukraine, albeit to a much lesser extent due to the different tactical environments of the two war zones.
Loitering munitions combine the attributes of missiles and Unmanned Aerial Vehicles (UAV) to provide a ‘hunter-killer’ weapon system, combining several tasks previously assigned to different platforms – aerial reconnaissance, target acquisition, battle management, attack and battle damage assessment. Loitering munitions can be operated individually, in groups, or in collaborative teams with other UAVs, enabling a few operators to remotely roam the battlespace, seeking targets of value, and eliminating those targets shortly after detecting them.
Loitering Weapons for the Individual Soldier
Today, loitering munitions are available in different shapes and sizes, from miniature platforms armed with hand grenade-sized warheads to effectively small aircraft with warheads closer to those of cruise missiles. The smaller types are often based on vertically launched or rotary winged quadcopter platforms. These include the STM KARGU, Rafael SPIKE FIREFLY, and IAI ROTEM L. Although very convenient for use by dismounted infantry, some quadcopters may require partial assembly before deployment. For more rapid deployment, forces can look to tube-launched loitering munitions, employing fixed-wing drones that are typically faster and are pre-packed in tube launchers with no assembly required. These include AeroVironment’s SWITCHBLADE 300, STM ALPAGU, and Uvision’s HERO 20. Most of these loitering munitions have been used in combat, and the US-made PHOENIX GHOST recently deployed to Ukraine most likely uses this configuration.
Based on the lessons learned with the first generation of small loitering munitions and the rapid advancement of drone technology, hybrid systems combining miniature rotorcraft and tube-launched systems have emerged; the Spear NINOX 40 MT and Defendtex DRONE40 represent such systems. Both offer the capability to fold a miniature quadrotor platform into a compact cylinder, then launch it from a handheld tube or standard underbarrel rifle grenade launcher. All three weapon classes are designed for use by the individual soldier. They have limited loitering time, use a simple camera adequate for close-range operation, use automated functions to simplify operation, and small warheads intended primarily for engaging unprotected targets. Their task is to provide their combat team with local situational awareness and the ability to strike soft targets of interest at relatively close ranges.
Hunter Predators
The next level of loitering munitions also function as ‘hunter-killers’, which effectively provide extended-range anti-tank and anti-matériel capabilities. The larger body diameter of these weapons allows mounting larger electro-optical assemblies, engines, and warheads, enabling them to provide higher-resolution imagery from higher altitudes, and greater effect on target than their smaller equivalents. The additional size and weight also allows mounting specialised warheads, such as anti-armour or anti-structure warheads, to allow more effective engagement of different target types. This class of loitering munitions can be divided into two subcategories – rail-launched and tube-launched loitering munitions. The first generation of this weapon class consisted of field assembled, rail launched munitions, such as the Elbit Systems’ SKYSTRIKER, Aeronautics’ ORBITER 1K, Zala KYB and LANCET, and WB Group’s WARMATE. These munitions can operate independently or rely on surveillance provided by other UAVs. An example of such a concept is the combination of ORBITER 3/ORBITER 1K to perform different roles.
Alternatively, users can also opt to use the same base platform configured with different payloads, as with the Warmate family of loitering weapons. The WARMATE R is a drone which can be configured with a reconnaissance payload using either day or thermal cameras with pan/tilt control and laser target designator, or alternatively the WARMATE R can be configured as a loitering munition when fitted with a warhead and a forward-looking camera.
As operational requirements have matured, operators have demanded faster deployment and quick launch capabilities. The HERO family of loitering munitions was the first to introduce a tube-launched loitering munition as the company moved from the rail-launched fixed-wing platform design to a cruciform-winged platform design. Other tube-launched weapons include Raytheon’s COYOTE, Aerovironments’ SWITCHBLADE 600, and Elbit Systems’ canister-based SKYSTRIKER. IAI’s MINI HAROP (also referred to as GREEN DRAGON) represents a larger version of this platform type, intended to be stored as part of a cluster of 16 canister launchers that can be carried on vehicles or small ships.
With a range of 10+ km and the ability to mount shaped charge warheads for dealing with armour, it isn’t surprising that loitering weapons are becoming mounted on armoured vehicles. Rheinmetall has recently unveiled their future main battle tank, the KF-51 Panther, equipped with a 130 mm cannon, integrated mini-UAV, and a pop-up launcher in the turret bustle capable of housing up to four HERO 120 loitering munitions. The US Marine Corps (USMC) has also selected the HERO 120 to fulfil their Organic Precision Fires- Mounted (OPF-M) requirement. As part of the requirement, UVision are providing their modular MULTI-CANISTER LAUNCHER (MCL), presently available in an eight-cell configuration, but slated to become available in four- and six-cell configurations. The USMC plans to integrate these MCLs on their:
- LIGHT ARMORED VEHICLE-MORTAR (LAV-M) 8×8
- JOINT LIGHT TACTICAL VEHICLE (JLTV) 4×4
- LONG-RANGE UNMANNED SURFACE VESSEL (LRUSV) unmanned craft.
Seeking High-Value Targets
Larger loitering munitions can be deployed at the operational level to locate and destroy targets of high value – such as command posts, communications nodes, radar and air defence sites, ballistic missile launchers, or smaller naval vessels. To execute these attacks, loitering munitions must be capable of operating at long ranges, with long endurance and must possess a relatively large warhead that matches the target type – for example high-explosive fragmentation (HE-FRAG) for area targets, or shaped charge warheads for engaging armoured or hardened targets. This class of munitions often use typically use sophisticated sensors and/or software, and may include elements of artificial intelligence to automate target acquisition.
Typical systems from IAI are the HARPY NG, HAROP, and MINI HARPY, designed to facilitate autonomous strikes at air defense or naval targets, employing the loitering weapon technologies. HAROP was employed in combat by Azerbaijan during the Nagorno Karabakh conflict. These assets were credited with successfully eliminating system elements of air defense systems, including S-300PS Transporter, Erector, Launcher (TEL) vehicles and a Transporter, Erector, Launcher, and Radar (TLAR) of the TOR-M2KM system. HAROP and HARPY NG are launched from truck-mounted containers; each unit carries nine missiles operated from a remote-control shelter. MINI HAROP and MINI HARPY can be deployed on tactical vehicles or small naval vessels, and additionally Israel and South Korea are jointly developing air-launched versions of those UAVs configured for launch from helicopters.
The Iranians employ truck-mounted launchers for their SHAHED 136 loitering munition. Each launcher consists of an ISO-type container with six UAVs stacked in a slanted launch position on launch rails. The SHAHED 136 loitering munition uses a rocket-assisted launch system and is powered by a pusher propeller driven by a small internal combustion engine (ICE), providing a reported range of approximately 2,000 km, and capable of precision targeting, effectively making this weapon equivalent to a small cruise missile. Iran also developed a faster loitering missile using a jet-propulsion. Known as the TYPE 358 missile, it has missile-like cruciform wing arrangement and is powered by a small turbojet engine which provides it with a range of approximately 100 km. The TYPE 358 was understood to be primarily intended for the engagement of low- and slow-flying aircraft.
MINI HARPY is provided with a dual seeker combining a radio direction finder (RDF) and an electro-optical/infrared seeker. This combination enables the MINI HARPY to locate and engage air defence assets, with the possibility of engaging them even when they turn off their radars.
Other drones like the Aerovironment BLACKWING and Spear NINOX 103 are designed to be deployed from submarines. Although both are presented as reconnaissance assets, sub-launched drones could likely be armed and used as disposable reconnaissance-strike systems, thus becoming loitering munitions.
Riding with UGVs
UGVs are becoming a popular choice for loitering munitions, as they can carry several loitering munitions to forward launch positions, keeping the operators protected from danger. As the UGV has all the necessary equipment to support loitering munition operations, such a deployment is valuable for operating swarms, as it enables the deployment, control, and coordination of multiple munitions with minimal risk to the operators. Another advantage of UGVs is their ability to route a UAV’s command links to other loitering munitions via its existing connection to the operator, thus extending the munition’s effective range without consuming additional spectrum resources.
Such UGVs could also be equipped with sensor payloads to support missions, particularly before the loitering weapons deployment. Typical examples are Rheinmetall’s MISSION MASTER UGV fitted with a six-cell MCL containing HERO 120 or WARMATE loitering munitions.
Such operations often involve different roles for airborne assets – primarily these would be divided into reconnaissance and strike assets. Reconnaissance drones are optimised for covering wide areas and performing close inspection of the potential targets. As expendable assets, strike assets would typically use less sophisticated payloads to verify and engage detected targets while the reconnaissance assets flying above would monitor the attack and perform post-strike battle damage assessment.
Future Directions
The future of loitering weapons seems likely to be the swarm – almost all developers of loitering weapons are already testing some types of swarming munitions, using dozens or even hundreds of platforms. Such operations are too complex to execute by human operators, therefore they are largely autonomous, with members of the swarm continuously sharing their status, position, attitude, and intent with all other swarm members. However, these are dependent on a human in the loop to make the decision to engage. The swarm manages all members in a distributed manner, allocating tasks such as lookout, decoy, and strike, enabling simultaneous strikes against multiple targets to come from multiple different directions. Use of such tactics could enable the rapid saturation of targets such as air defence systems. Since swarm operations require considerable setup, automating the launch sequence is a necessary part of the process. Raytheon has developed such a launcher for its LOCUST loitering weapon system and has demonstrated its operation with several dozens of loitering munitions. The Halcon company of the UAE Edge group is also developing a 21-cell swarm launcher for HUNTER 2-S loitering munitions.
The TRX tracked UGV – a concept vehicle designed by General Dynamics Land Systems (GDLS), is a further example of development in the field of the swarm concept. TRX can carry 26 SWITCHBLADE 600 loitering weapons along with 24 SWITCHBLADE 300s. A tethered quadcopter UAV is also deployed from the platform to provide an elevated view of the battlefield. With up to 50 loitering weapons deployed, TRX will be able to deploy a swarm of loitering weapons to cover a battlefield sector from above, providing a small number of remote operators the capability to locate and engage targets with minimal risk. L
