In 1980, news media reported that lasers, a type of directed energy weapon in development since the 60s, could transform warfare in the next decade. That transformation did not happen then, yet the hype around directed energy weapons as the future of air defence remains relevant today, particularly in countering uncrewed aerial systems, more commonly known as drones.
Despite the recurring gap between expectations and reality, directed energy weapons have repeatedly attracted strong interest and investment. While there has been progress in the maturation of this technology, the nature of warfare has also changed since the Cold War when this technology was first conceived. This raises the question: what implications might integrating directed energy weapons into layered air defence have for countering drones and international security more broadly?
Directed energy weapons emit highly focused energy that travels at the speed of light to disable, degrade or destroy targets, enabling faster engagement compared to physical projectiles. The term covers a wide range of technologies, each differing in their underlying physics, impact on the target and level of maturity.
The most mature types, high-energy lasers and high-power microwaves, are widely discussed in the context of their perceived cost-efficiency and defensive potential against the mass proliferation of drones. Currently, high-energy lasers receive more attention in the context of countering drones due to greater precision and longer effective range than high-power microwaves, with several States having already deployed the former in limited instances.
So, what could hamper the use of this technology for defensive purposes? During UNIDIR’s technology briefing on the topic, panellists pointed out that some of the more consequential challenges are operational rather than purely technological.
Effective range is one of the primary operational challenges, as both high-energy lasers and high-power microwaves can only impact targets within a limited range.
“Old” technology, new economics
Despite operational and technological challenges to directed energy weapons, there is an interest in examining how they may be used in air defence, especially given the rising use of drones, by State and non-State actors. Low-cost drones have altered the economic balance between air offence and defence, pitting interceptor missiles costing as high as millions of dollars against considerably cheaper threats.
Consequently, the interest in directed energy weapons is largely driven by the promise of cost-efficiency. The cost-per-shot of an operational high-energy laser or high-power microwave often equals the cost of electricity used, which can be as little as a few dollars, making them appealing against inexpensive threats. However, this narrative assumes the operational maturity of these systems, whereas in reality, even the most mature ones are facing challenges in progressing from testing to scaled deployment.
Speaking at UNIDIR’s event on the matter, Richard Hoad highlighted that the high upfront cost of developing an operational directed energy system is a potential barrier to industry and the customer, nuancing the simplified economic pitch driving the interest in directed energy weapons.
A related issue is revenue generation for the industry to offset upfront costs, Hoad further noted. Unlike traditional munitions, which have a finite lifetime and allow industry to generate revenue through the replenishment of stockpiles, directed energy weapons do not follow the same lifecycle, leaving the question of how industry might offset upfront costs still to be determined.
Despite decades of research and development, these weapons’ capabilities still require a continuous and extensive funding commitment. Nonetheless, smaller companies entering the market alongside large defence contractors could contribute to the advancement of the capability, reinforcing interest and investment.
The hardening of aerial systems
Besides international law implications, a scaled deployment of directed energy weapons could also impact military innovation and arms control efforts. The renewed interest in the development of these weapons in response to the mass proliferation of drones may prompt drones to adapt, which could in turn drive further adaptation of directed energy weapons, creating a familiar measure-countermeasure cycle seen with emerging military capabilities.
Since high-energy lasers and high-power microwaves operate on different principles when engaging targets, the pathways for hardening drones against each differ accordingly:
- High-energy lasers impact a target by focusing a beam of light on its surface, so hardening focuses on protecting the exterior with reflective and ablative coatings, as well as protecting optical sensors, which are especially vulnerable.
- High-power microwaves target the internal electronics of a system using pulses of microwave energy that can enter through antennas and other points of entry, so hardening focuses on the electromagnetic shielding of the airframe and the use of filters at these points to block or weaken incoming energy.
At the same time, completely shielding drones remains unfeasible as long as they must retain Global Navigation Satellite System (GNSS) positioning and communications with remote operators. Increasing autonomous navigation could reduce drones’ reliance on GNSS and communications with remote operators. Already explored in response to electronic warfare threats, this approach could also make drones more resilient to high-power microwaves by enabling complete shielding. Altogether, these alterations would also affect their production costs, cutting into the economic logic that revived the interest for directed energy weapons in the first place.
On the other hand, while some drones may harden and become costlier to produce, low-cost, disposable drones could still be used to counter high-power microwaves. Edl Schamiloglu noted that there is no hard maximum amount of drones a high-power microwave could target within the reach and direction of its beam.
Building on this, David Hambling suggested that swarms comprising a large number of drones could attack from multiple directions at once, overwhelming such systems. In response, defenders may deploy additional high-power microwave systems, triggering a cycle in which larger drone swarms are met with a bigger deployment of directed energy weapons.
From defence to offence
Directed energy weapons are generally most effective in short-range defence roles, owing to their limited effective range. While most systems are either ground-based or mounted on naval or ground vehicles, directed energy weapons might also be integrated in aircraft as power supply systems evolve.
Panellists at UNIDIR’s technology briefing similarly raised the possibility of integrating these weapons with drones, highlighting that it may be one solution to the range restriction in counter-drone applications. Hambling further pointed out that such a development would also open the door to offensive applications of directed energy weapons technology.
This is particularly concerning in the case of high-power microwaves, which can affect a wider area than high-energy lasers and therefore pose greater risks to civilian infrastructure. Even when used defensively, the former may unintentionally affect a friendly electronic system.
In offensive scenarios, the risk becomes more acute when military targets are situated near civilian infrastructure, potentially disabling civilian structures, including critical infrastructure. This concern is heightened by the growing prevalence of urban warfare, where the effects of wide high-power microwaves in densely populated and structurally complex environments could carry serious humanitarian consequences.
Strip away the sensationalist claims that have persisted for decades, and a more realistic assessment among experts emerges: Directed energy weapons will likely become one layer of a complex air defence.
For the disarmament community, this evolving capability still warrants consideration, from the dynamics of weapon development and use to the humanitarian risks that may follow if directed energy weapons shift from defensive to offensive applications.
