The tactical problem is simple to state and fiendishly hard to solve. Adversaries can now mass relatively cheap unmanned systems to impose an attrition tax on defenders. Defenders in turn are pursuing directed energy tools that promise deep magazines and low marginal cost per engagement. The engineering tradeoffs collapse into three variables: physics of propagation, effects modality, and systems integration. I will walk through those variables and show where high-energy lasers and high-power microwaves are complementary and where neither is a silver bullet.

What swarms look like in practice

Recent conflicts have crystallized the swarm problem into two operational vectors. First, low‑cost loitering munitions and cheap attack drones have been produced and launched at scale to saturate air defenses and inflict cumulative damage. Examples from the Russia‑Ukraine war show repeated mass launches of Shahed‑type loitering munitions and related UAS that force defenders to expend high‑end interceptors or allocate scarce electronic warfare and short‑range defenses on a sustained basis. That operational picture is why militaries are willing to trial new, electrical‑energy based defeat mechanisms.

Directed energy tools on the table

Two distinct categories of directed energy (DE) are receiving the most attention for counter‑swarm work.

  • High‑energy lasers (HEL). These deliver focused optical energy to heat, burn, or structurally weaken a target. Contemporary tactical systems operate across roughly 10 kW to 100+ kW classes for ground and shipboard roles. Laser weapons engage with line of sight, require beam pointing and tracking, and typically need seconds of dwell time on small UAS to cause mission kill. Laser prototypes and demonstrations have proven kill chains against quadcopters and small fixed wing drones in controlled tests.

  • High‑power microwaves (HPM). These emit pulsed or continuous electromagnetic energy to disrupt or permanently damage electronics across an illuminated volume. HPM systems are explicitly attractive for one‑to‑many engagements because a single burst can upset many unshielded platforms inside the beam cone. HPM proponents position their systems as area effects weapons that can neutralize swarms without kinetic debris. The U.S. Army awarded prototyping work and accepted early IFPC‑HPM prototypes as part of rapid fielding efforts.

Physics and operational limits

No weapons system operates in a vacuum. For lasers the dominant limiting factors are atmosphere and power management. Molecular absorption, aerosols, rain, fog, and thermal blooming degrade beam irradiance on target and increase required dwell time. Adaptive optics can mitigate some turbulence but cannot eliminate the fundamental losses imposed by weather and particulate loading. These are engineering constraints, not political ones, and they matter because they determine how often a laser can produce a tactical kill in real operating conditions.

HPM has a different set of physics constraints. Microwaves couple into electronics through antennas, wiring, or apertures. Effectiveness scales with field strength at the target and with the vulnerability of the target electronics. HPM is less sensitive to fog and rain than optical beams, but propagation range and on‑target coupling still fall with distance and with intervening structures. The broad cone of an HPM also raises rules‑of‑engagement and collateral‑effects questions: any unshielded friendly or civilian electronics inside the beam could be disrupted. The U.S. government literature recognizes both the potential area advantages of HPM and the need for careful safety and interoperability testing.

Economics and operational math

One reason directed energy has moved from laboratory curiosity to field trials is economics. Solid‑state lasers and HPM devices convert electrical power into effects. Once the platform exists, the marginal cost of firing a laser shot is dominated by fuel or grid power and wear items. Congressional and audit summaries note that cost per shot for electrical DE engagements can be in the single‑digit dollar range for energy alone, which contrasts sharply with tens of thousands of dollars or more for interceptor missiles. That cost asymmetry changes force calculus in attrition scenarios where adversaries flood the sky with low‑cost UAS. But the capital, integration, and lifecycle costs of DE systems remain significant, and logistics shift from missile magazines to reliable power, cooling, and spare parts.

Tempo and magazine depth

Swarms stress two resources: engagement rate and sustained magazine depth. Lasers win at magazine depth as long as a platform can generate electricity and dump heat. HPM wins at instantaneous area effect by potentially taking many platforms off the network at once. In practice the right answer is layered. Use HPM or electronic attack to degrade or blind a cluster of swarm members, then apply lasers or small kinetic interceptors to the stragglers or to targets of higher value. That layered approach reduces the risk that any single environmental factor or countermeasure will break the defense.

Countermeasures and the arms race

Swarm developers are not static. Simple hardening, better shielding, analog control paths, and autonomous peer‑to‑peer behaviors reduce the effectiveness of both HEL and HPM. On the HEL side, targets can reduce exposed absorptive surfaces, increase distance, or incorporate sacrificial outer structures. On the HPM side, designers can add filters, transient suppression, or redundant logic paths. The pace of adaptation on both sides is rapid and driven by commercial electronics cycles. That dynamic means both directed energy suppliers and users must prioritize software‑driven tuning and modular upgrades so deployed systems can respond to evolving countermeasures.

Integration and rules of engagement

From a systems engineering point of view the hardest work is integration. Effective DE employment requires fused sensors, rapid C2, validated kill assessment, and power and thermal infrastructure sized for peak load. The U.S. Army and industry have pursued rapid prototyping pathways for IFPC‑HPM and vehicle‑mounted HELs precisely because tests reveal integration problems that are invisible in lab reports. Those prototypes reached government acceptance testing and early field use under rapid acquisition timelines. Operational doctrine must answer when to use nonkinetic, area‑affecting HPM versus a precision HEL shot, and how to deconflict effects in complex electromagnetic environments.

Ethics, law, and escalation risk

HPM systems can produce nonkinetic effects across civilian infrastructure. That raises legal and escalation risks not present for a single interceptor missile. Likewise lasers that burn or blind sensors raise concerns around proportionality and humane use. Operational manuals and acquisition decisions must factor in collateral risk, target discrimination, and verification of system behavior under degraded sensory conditions.

Where each technology is likely to be decisive

  • High‑energy lasers. Best for point defense of high value, fixed sites in clear line‑of‑sight environments. They are economically favorable for repeated engagements against small UAS and offer precise, reversible escalation options when paired with graduated engagement rules. Use case: base perimeter defense and ship self defense against low‑end UAS when atmospheric conditions permit.

  • High‑power microwaves. Best for area suppression and for defeating networked swarms that rely on shared electronics or common navigation and comms links. HPM is attractive where you need to rapidly deny an area to many small systems, especially when weather rules out optical engagement. Use case: convoy or forward operating base when a massed swarm makes individual engagements impractical.

Practical recommendations for force planners

1) Treat DE as part of a layered counter‑swarm architecture. Neither HEL nor HPM is a stand alone solution. Mix sensors, EW, DE, and low‑cost kinetic interceptors to match the threat mix. 2) Design logistics around power and thermal margins not ammunition magazines. That is the single biggest shift in supply chain thinking for DE weapons. 3) Prioritize modular, software‑defined DE systems that can be updated against new countermeasures. Hardware upgrades will always lag the pace of swarm innovation. 4) Invest in realistic environmental testing. Lab kills are necessary but not sufficient. Atmospheric propagation and real operational clutter determine campaign effectiveness. 5) Clarify legal and escalation rules for HPM employment before fielding. Area effects are powerful but politically sensitive.

Conclusion

As of today the balance of evidence suggests directed energy is not a panacea but rather a transformative layer. Lasers give defenders a low marginal cost, precise option that reshapes economics in attrition fights. HPM offers area suppression that changes engagement geometry. Both are advancing rapidly from prototype to fielded capability and both owe their operational utility to how well defense planners build power, cooling, sensor fusion, and legal rules into doctrine. The winners will be the militaries that treat DE not as an exotic new weapon but as a systems problem rooted in physics, logistics, and networked operations.