Fog of War: The Biggest Challenge for Naval Laser Weapons
Laser weapons require line of sight and atmospheric stability, and the ocean provides neither.
Last week, Vice Chief of Naval Operations Adm. James Kilby sat in front of Congress and delivered a sobering update on the US Navy’s High Energy Laser with Integrated Optical Dazzler and Surveillance (HELIOS) laser weapon. The system, billed as a 60 kilowatt high-energy laser meant to zap drones and dazzle sensors, is currently operating at just one-third of its rated output aboard the Arleigh Burke-class destroyer USS Preble.
“We had some problems during testing,” Kilby told lawmakers during a House Appropriations Committee hearing on May 14, “but now we’re up to one-third of the power and we’re going to continue to test the weapon system to make sure it works.’
Despite a growing chorus of commanders and lawmakers calling for the rapid fielding of directed energy weapons to counter the rising threat of cheap weaponized drones, Kilby’s reveal represents a major blow to the Navy’s laser weapons ambitions, suggesting that HELIOS may not be ready for prime time just yet.
But HELIOS’s incomplete power delivery isn’t the only problem facing the system — and arguably not even the most serious one. Even if it were firing at full 60 kw today, it would still be battling a far more persistent, unsolvable adversary: the air itself.
Welcome to the literal fog of war, where high-energy lasers run face-first into the fundamental physics of our planet’s atmosphere.
Lasers are precision tools. They require a clear, uninterrupted path to deliver focused energy to a target. In lab conditions, or clean dry air, they’re devastating. But as a 2020 Naval Postgraduate School capstone report on counter-directed energy weapons lays out in some detail, real-world conditions are a different story.
The physics are simple but unforgiving. As a laser beam travels through the atmosphere, its energy is degraded by scattering, absorption, and turbulence. Water vapor, dust, salt aerosols, and temperature fluctuations all contribute to bending, diffusing, or bleeding off energy from the beam. According to the report, even a small shift in the laser’s wavelength — from 3.7886 to 3.7902 microns — cut beam transmission through sea-level air from 90% to 50% over 10 kilometers. That’s a major performance cliff triggered by what amounts to a rounding error.
This is certainly the case for land-based high-energy laser systems deployed to environments like, say, the Middle East, where dust storms are prevalent. But this is especially bad news for lasers deployed at sea, where humidity, sea spray, and thermal layering are baseline conditions. These are not minor edge cases: they are the operating environment.
There’s a reason HELIOS has struggled to gain operational traction, and it’s not just technical growing pains. Shipboard lasers have been in the works since the 30 kw AN/SEQ-3 Laser Weapon System, also known as the XN-1 LaWS, was installed aboard the USS Ponce in 2014. That system, too, performed well in testing but never graduated into a fleet-wide program of record.
Why? Because the ocean is not a lab – at least, not for lasers. It’s wet, salty, and full of particles. It deflects and scatters energy. Lasers require line of sight and atmospheric stability, and the ocean provides neither.
The NPS report walks through a number of atmospheric effects that degrade laser performance. They include thermal blooming, where the laser heats the air in its path, causing a local refractive index change that spreads the beam; turbulence, where air molecules act like thousands of tiny lenses that randomly defocus the beam mid-flight; and aerosols, like salt and smoke, which scatter and absorb photons before they reach the target. These effects are baked into the physical environment in which Navy laser weapons must operate, and they’re exacerbated the moment the ship moves into contested littoral zones where the battlespace fills up with smoke, dust, and decoy aerosols.
Then there’s the issue of dwell time. Even if a naval high-energy laser can generate 60 kw of power or more, it still has to deliver that energy to a target with enough precision and intensity to cause real damage. That means maintaining coherent beam focus for 5 to 10 seconds, according to modeling cited in the NPS report – and that’s only if the beam isn’t degraded by the atmosphere. If a drone is maneuvering, covered in reflective coatings, or flying through fog, smoke, or salt spray, the dwell time needed for a hard kill could stretch beyond engagement feasibility, meaning fewer viable opportunities for a effective laser engagement under real-world conditions.
To be fair, the Navy isn’t flying blind. According to a March 2025 Congressional Research Service report on the service’s shipboard laser weapon programs, ongoing efforts to mitigate these limitations include adaptive optics to pre-distort beams based on expected turbulence and wavelength selection, where the system finds a “sweet spot” in the electromagnetic spectrum where scattering is significantly reduced. But these solutions are partial, expensive, and slow to field.
While the Navy wrestles with HELIOS’s challenges, other nations are also pushing forward with their own naval laser weapon efforts. China has reportedly tested laser systems aboard warships, likely intended for sensor disruption or counter-drone missions, though detailed capabilities remain opaque. The United Kingdom’s DragonFire program is aiming to install laser weapons aboard four warships for testing within the next few years. Japan is investing heavily in shipboard laser weapons R&D. Meanwhile, Israeli defense tech company Rafael is evaluating its so-called “Iron Beam” laser weapon for potential maritime adaptation despite the fact that the land-based system has yet to go into operational service with the Israeli military. More concretely, the German military conducted an at-sea trial of a laser weapon demonstrator in June 2022, while the French military carried out a similar test the following year. None of these programs appear to have overcome the fundamental environmental and integration challenges that have hampered the US Navy’s efforts, but they underscore a growing international consensus: directed energy at sea is strategically desirable, even if technically elusive.
Despite this, there’s clearly no panic over a “laser gap” eating away at Navy decision-makers at the moment. As Kilby himself noted at the Navy League’s Sea-Air-Space symposium in April, the Pentagon is in no rush to go “all in” on buying naval weapons that can’t guarantee effectiveness.
“There’s a push in activity,” he told reporters at the time. “It’s for me not to buy something that doesn’t work, so I need to test it and make sure it’s actually actionable.”
