They stuffed a real-life ray gun into a 747 to shoot down ballistic missiles and stuck a laser on top of a Humvee to zap roadside bombs. For more than 50 years, the United States military and its researchers have tried to develop laser weapons. None of them panned out.

But now, the US Army is about to make a working laser weapon an official part of its arsenal. The Pentagon is poised to sign a contract to acquire and rapidly deploy what’s called an Enduring High Energy Laser in and around bases across the world to defend them from drone attacks, according to sources familiar with the matter. The official announcement could come as early as this week. When the deal is signed, it will mark the first time that the US military will have committed to equipping its forces with laser weapons in significant numbers.

“For years, lasers were going to be the future, and they never really came to their own. Now, they’re actually coming to their own,” Mark J. Lewis, the former Air Force chief scientist, tells WIRED.

The Iran and Ukraine wars have shown that drones are now so cheap, so plentiful, and so deadly that they’re impossible to stop with any single countermeasure. Some of the traditional ones have been particularly clunky. During the early days of the Iran conflict, the US even resorted to firing $4 million Patriot missiles at $35,000 Iranian drones—a waste of money, and a move that depleted the American interceptor stockpile.

Modern lasers, on the other hand, never run out of ammunition. “Basically, you can keep firing them as long as you’ve got power,” Lewis says. “There are some other issues with lasers, including how rapidly you can refire and recharge. But if you solve those problems, then suddenly you’ve got a pretty nifty way to help counteract things like a drone swarm attack.”

That’s one reason why the US military, at this moment, has either deployed or is actively testing a half-dozen laser weapons systems, according to the Laser Wars newsletter. The Navy has installed laser “dazzlers” on two of its ships to blind drones’ electro-optical sensors. The Air Force’s command for Europe and Africa has sent Boeing’s Compact Laser Weapons System “to locations across the theater.” In late June, Defense Secretary Pete Hegseth traveled to the Army’s test range in White Sands, New Mexico, for a demonstration of all sorts of directed-energy weapon projects.

The deployments haven’t all gone great. Four vehicles equipped with Raytheon air-defense lasers were yanked from the Middle East after poor reviews from soldiers. One laser, built by the defense contractor AeroVironment and positioned along the southern US border, accidentally zapped a party balloon in February, causing the Federal Aviation Administration to briefly close the airspace around El Paso, Texas. Once it was reopened, the laser shot down a Border Patrol drone by mistake.

Despite such mishaps, the Army appears ready to go beyond the one-offs and the experiments. In fact, in some ways, the accidental kill helped make the case for the laser, proving it could actually take out such a drone.

The Pentagon and its suppliers had been scrambling to field something, anything to defend against mass-produced, low-cost attack drones. They’ve rolled out radio frequency jammers, microwave weapons, an array of missiles, drones designed to kill other drones, even copies of the Iranian robots. None of them in isolation have been enough. On March 1, an Iranian drone killed six US service members and injured 30 others.

Pentagon and FAA officials went to White Sands less than a week later for a demo of an AeroVironment laser and assurances it could operate safely in a crowded airspace, according to The New York Times. (Lt. Gen Frank Lozano later said at a DC think tank event that the system had showed “a lot of recent promise and capability out at White Sands,” adding that the Army was “negotiating a contract with AeroVironment right now for the Enduring High Energy Laser system.”)

Two days after the White Sands display, President Donald Trump hyped the directed energy weapons’ capabilities.

“The laser technology that we have now is incredible,” he told reporters at his Doral, Florida club. “It’s coming out pretty soon, where literally lasers will do the work of—at a lot less cost—do the work of what the Patriots are doing.”

Now, the Army is expected to sign a contract worth hundreds of millions of dollars with AeroVironment. According to the Army’s original request for information, that would be for up to 20 of the weapons. They’re supposed to be compact enough to fit inside in a four-by-seven foot container, or atop an all-terrain vehicle. And as Trump noted, they’re supposed to be powerful enough to knock out one-way attack drones# like the Shahed-136, the workhorse of Iran’s deadly unmanned arsenal. (Neither the Army nor AeroVironment agreed to comment for this story.)

But the truly novel development is that the Enduring High Energy Laser, or E-HEL, will be an operational “program of record,” military-speak for a formally approved piece of kit, officially inscribed in the Pentagon’s five-year budget. That’s the military’s sign to itself that this is for real, and a signal to contractors to ramp up production. “Program of record indicates a wider cultural acceptance of the new technology as a military capability,” says Craig Robin, who ran the directed energy portfolio for the Army’s Rapid Capabilities and Critical Technologies Office. It’s the first time the Army has ever done so with a laser weapon.

The basic physics of lasers have been well-understood for decades: Infuse an atom with enough energy and it goes into an “excited state,” in which the electrons orbit farther away from the nucleus. When the electrons come back down, they emit photons, and each one passing an excited atom triggers it to emit an identical photon: same frequency, same phase. Bounce that cascade between mirrors so it keeps building, and you get a powerful, coherent beam.

Which material, or “gain medium,” determines the light’s frequency; almost anything will work. “My own favorite is that a mixture of alcohol and quinine solution can actually be made to fluoresce, so you can actually do a laser martini,” Lewis says.

But just because you can make a laser martini doesn’t mean you should. Different gain media can produce different levels of power, at different levels of efficiency. That 747 used a mixture of chlorine, hydrogen peroxide, iodine, and other chemicals; it was powerful but toxic. The laser-equipped Humvee started out with a weapon that relied on a synthetic garnet crystal made of yttrium and aluminum; nontoxic but weak.

Eventually, most military laser-makers all turned to a single solution: “fiber lasers,” which rely on bundles of glass wires infused with rare-earth ions. They absorb energy more efficiently than the others, are better at releasing heat, and allow for an almost perfectly focused beam. Each individual fiber laser can’t produce that much power—just a few kilowatts—but they can be bundled together for weapons-grade work. And besides, the small drones these weapons would be used against don’t take that much power to take out.

“Exciting” the atoms inside those fibers got easier, thanks to advances in the semiconductor diodes (think LEDs, but with laser lights) that pump energy in, and get the chain reaction started. Advances in machine vision have helped the beams stay locked on target, while adaptive optics—mirrors that flex in real time to cancel out the shimmer of the atmosphere—keep them tightly focused. Put it all together, and you’ve got the makings of a laser weapon.

“The science for directed energy is largely done, and now we are in the engineering phase of it. So the engineering part of it makes it cheaper, smaller, and more proliferated,” Emil Michael, the under secretary of defense for research and engineering, told Congress in May.

It’s a song we’ve heard before. “The ray gun has finally become a reality,” The New York Times announced in 2008. A Popular Science cover story from 2006 showed illustrations of laser-firing stealth fighter jets and asked, “Can scientists end the era of bombs and bullets?”

I wrote that story. And the answer, then and now, is no.

Rain and fog stop lasers short. And lasers have to be fired at one target at a time, a few seconds per target. (Just look at this rather awkward demonstration of 60 Minutes host Leslie Stahl operating an AeroVironment weapon.) “So if you’ve got 1,000 drones coming in, you’re not going to hit every single one,” says Scott Keeney, the CEO of nLight, a company that provides lasers to companies like AeroVironment and just won its own Pentagon contract, worth up to $627 million, to develop a laser that can take out a cruise missile. What’s more, lasers—especially the powerful ones he’s developing—keep going and going, even into orbit. “They just don’t stop,” Keeney says. Which means they could not only be a danger to aircraft but to satellites too.

In fact, the whole idea of swapping traditional munitions for lasers is “really dumb,” Lewis says. “The gun works fine. Why would you replace it with the laser? Use the laser in ways that you can’t use the gun.”

Especially when the metaphorical gun, in this case, is a multimillion-dollar-per-shot interceptor system, and the target is a cheapo killer drone. Better to shine a beam of lethal light at it instead.

The post Landmark Deal Would Officially Add Laser Weapons to US Army Arsenal appeared first on Wired.