The incorporation of artificial intelligence (AI) in the military produces new and smart systems that redefine how the combat force is projected on a battlefield. Weapon systems are increasingly getting smaller, more flexible, more precise, more intelligent, and more robust. Loitering munitions, also dubbed as kamikaze drones, are the most recent example in this regard. These munitions fall in-between drones and missiles, and their loitering capability allows them to detect and track potential targets for an extended period before engagement. The use of loitering munitions in warfare, irrespective of the risks involved, reflects that for military planners, the efficacy of these munitions overrides the risks.
Loitering munitions are drones with an integrated warhead designed to engage beyond visual line-of-sight targets (BVLOS). Paul Scharre, in his book Army on None, has defined loitering munitions as fully autonomous weapon systems which can search, identify, decide, and engage targets independently without any human intervention. In general, loitering munitions are suicide drones which have a high degree of autonomy and carry explosive payload onboard. Unlike traditional combat drones, which carry weapons, loitering munitions are weapons themselves. In concept, loitering munitions work like cruise missiles but can loiter in flight like drones for extended durations. But the human input in these systems, from launch to engagement, is far less than that of drones. In practice, the extent of autonomy in such munitions varies depending upon the level of human control desired as per the threat environment. But the working principle remains the same for all loitering munitions.
One of the earliest examples of loitering munitions in modern history is Israel’s Harpy drone. Harpy drones were designed to loiter over a wide area, search out radio emissions, and then engage the source of radio emissions by hitting the target. This indicates that harpy drones are designed to be used for suppressing/destroying enemy air defences (SEAD/DEAD) – an approach followed by radar-homing missiles like US HARM. However, unlike human-directed anti-radiation missiles following a well-directed flight path, radar-homing loitering munitions have less or no reliance on a human operator, can loiter over the target zone for a longer time, and utilise a way-point flight path for exploiting the vulnerabilities in enemy’s defences.
The proliferation of loitering munitions on the battlefield despite the risks involved indicates that for military planners, the efficiency of these munitions outweighs the risks. From a purely anti-radiation weapon to a full spectrum weapon, loitering munitions are rapidly finding more and more applications in future military operations.
In general, loitering munitions offer four major advantages over traditional weapon systems. Firstly, loitering munitions offer extensive launch and engagement capability. These weapons can be launched from land, air, and sea and can be integrated with a variety of launch mechanisms ranging from man-portable to mechanical carriers. For example, these weapons can be launched from man-portable systems, combat vehicles, including armoured vehicles and artillery, rotary and fixed-wing aircraft, warships of varying tonnage, and even other drones controlled by a human operator. At the tactical level, loitering munitions have significantly augmented over-the-horizon targeting capability. Many kamikaze drones are dual purposes: they also have recon capabilities as they can relay target information back to the operator. Therefore, these systems can operate independently without relying on the sensor coverage of other units and, on certain occasions, can be used beyond line-of-sight sensor coverage.
Secondly, these weapons are cheap, smaller in size, and thus can be widely deployed at a wider scale across the battlefield. On the economic scale, loitering munitions are far cheaper than cruise missiles and anti-tank guided missiles (ATGMs). For example, Switchblade suicidal munitions, with a per unit price tag of $6000, are far cheaper than Javelin ($176,000) and Hellfire ($150,000) missiles. Another interesting feature of these munitions is their ability to be re-used if they have not found a feasible target. Many kamikaze drones can autonomously return to the launch position for re-usage, thus saving money.
Thirdly, these munitions offer an enhanced distinguishing capability to differentiate potential targets from non-combatants. Unlike mortars and artillery, which cannot discriminate between combatant and non-combatant and follow predictable firing trajectories, these munitions can identify a target and formulate feasible engagement sequences. Some loitering munitions have wave-off capability, which essentially allows the operator to abort a previously assigned target and re-engage a more suitable target if necessary. Moreover, few kamikaze drones, like Switchblade, have a forward-facing blast that ensures targeted engagement with minimum collateral impact. This ensures superior engagement capability in a highly dynamic combat environment with minimum risks.
Lastly, these munitions are hard to detect and intercept. These kamikaze drones are usually made up of composite structures and are smaller in size than traditional cruise missiles. Therefore, these weapons have low radar cross-section (RCS) and cannot be detected easily and timely by radars and passive sensors. With these munitions being cheap and easy to produce, they can be used to saturate enemy air defences. In most cases, the surface-to-air missiles (SAM) used to intercept these drones are several times more expensive than the target being engaged. Similarly, since these munitions are steerable like drones, vulnerable spots of enemy defences can be exploited to engage high-value and well-protected targets.
Kamikaze drones were used extensively for the first time by Azerbaijan in the Nagorno-Karabakh conflict. Azerbaijan innovatively employed these suicidal drones for engaging targets, particularly air defence systems, from long ranges. These stand-off engagements helped Azerbaijan to achieve military objectives without risking the vulnerabilities of the traditional battlefield. The conflict also highlighted the need for Full Spectrum Defence, particularly short-range air defences, for intercepting such munitions and safeguarding high-value assets.
Kamikaze drones have also been used by both sides in the Russia-Ukraine conflict. The United States handed over Switchblade suicide drones to Ukraine for defence against Russian ground forces. Switchblades are launched like mortar, can loiter above the potential enemy area, and then glide towards their target after locking it. Russia, in response, used the Aero-Kub suicide drone. In the initial phase of the conflict, both these drones failed to deliver any remarkable outcome on the battlefield. However, at a later stage, Iran-supplied Shahed-136 kamikaze drones, being used extensively by Russia, have earned the reputation of a fearsome weapon. Shahed-136 cannot engage mobile targets and is useful against fixed installations. But these drones are cheap and can be used in large numbers in order to penetrate Ukrainian air space and strike targets of varying natures. These drones may not have turned the tide of war in Russia’s favour, but indeed have imparted significant psychological impact on its victims.
Loitering munitions have numerous challenges associated with their effective and safe employment on the battlefield. First of all, a suicidal flying weapon with no supervisory human control increases concerns associated with accountability with respect to laws of armed conflict (LAC) and international humanitarian law (IHL). Particularly in the hands of violent non-state actors, these weapons will pose major security as well as accountability challenge.
Secondly, loitering munitions present a dilemma as far as the level of autonomy and degree of human control are concerned. Such munitions can either employ superior autonomy to operate in a communication-denied or electronically contested environment but at the cost of human control. Such weapons with technologies that ares still in the experimental phase are too risky, particularly when escalation control is required and ethical grounds are put under consideration.
Thirdly, loitering munitions rely on AI algorithms which, in certain circumstances, are prone to errors or technological limitations. Such shortcomings lead to miscalculations which can yield inadvertent and unintentional outcomes in combat like blue-on-blue incidents, collateral damage, and unintended target engagement.
Fourth, the usage of loitering munitions might not be economically feasible in certain roles. For example, for a saturation ground strike, a traditional multiple rocket launch system (MLRS) would be more practical than using swarms of suicidal drones. Similarly, standard mortar or artillery systems can economically provide sustained fire support than loitering munitions launched from a similar mechanism – like the US switchblade.
And finally, characteristics like targeting flexibility, wave-off capability, and precise force engagement increase the temptation to employ these weapons with more confidence and in contested areas. This increased use of violence and risks of collateral damage would yield major psychological consequences at the societal level.
The proliferation of loitering munitions on the battlefield despite the risks involved indicates that for military planners, the efficiency of these munitions outweighs the risks. From a purely anti-radiation weapon to a full spectrum weapon, loitering munitions are rapidly finding more and more applications in future military operations. After air-land operations, these weapons are also entering the naval arena. These weapons can be armed on smaller boats to increase their lethality. A growing trend has been observed in defence exhibitions around the globe showcasing new and innovative kamikaze drones for defence markets.