ARMIES HAVE dreamt of firing laser weapons for a long time. A lab funded by America’s Defence Department demonstrated one in 1960. But decades of development failed to produce a practical weapon, and the ambition waned. Now it is back. Last year America reportedly used a high-energy laser (HEL) to down drones aimed at its forces in the Middle East. Israel and Russia have both recently used HELs to foil drone attacks. Ukraine may soon do the same. Why are laser weapons suddenly useful? And what role could they play in future wars?

The Martians had a heat ray that could destroy the Royal Navy’s battleships, but that was in “The War of the Worlds”, a 19th-century work of science fiction. HELs are not high-energy enough for that. To seriously damage a warship or tank would require megawatts of power—a noticeable proportion of the output of a conventional power plant. HELs produce kilowatts, ie, thousandths of a megawatt. Even aircraft can survive bombardment by HELs.

For a while missiles looked like potential prey. They have thin skins and are packed with fuel and explosives. Merely damaging the shell of a supersonic missile can create drag, causing it to tumble out of control. And, no matter how fast the missile, laser beams, which travel at the speed of light, can catch up to it.

President John F. Kennedy gave a laser-missile-defence project the highest national-security priority after the Cuban missile crisis in 1962. But missiles turned out to be difficult targets. They’re not as fast as lasers, yet they are still hard to intercept. In 1973 a laser downed an aerial target at White Sands Missile Range in New Mexico, but it was something a little slower than a missile, perhaps a small radio-controlled aircraft.

The advent of the small drone as a weapon in the 2010s has given lasers a target they can handle. The Russian and Ukrainian armed forces have launched attack drones, as have the Houthi militia in Yemen. They are becoming ubiquitous in war. Conventional air defences can shoot them down, but many of the missiles these systems fire cost millions of dollars and are in short supply. Lasers, on the other hand, cost just a few dollars per shot and their ammunition is limited only by their power supply. Advocates say they’re the ideal drone killers.

America fielded a laser system in the Persian Gulf in as early as 2014, to destroy small boats and other “asymmetric threats”, but did not use it. It probably first fired one in battle last year. A 20-kilowatt LOCUST system, the size of a small garden shed and weighing some 1,500kg, reportedly downed drones launched at a military base in the Middle East, probably by an Iran-backed militia. This year Israel released video of its lasers shooting down drones fired by Hizbullah, a Lebanon-based militia. The Israel Defence Forces claim that they have taken out “dozens” of drones. Analysts believe that Israel is using the Keren Or (Lite Beam) system made by Rafael, an Israeli firm. It’s a ten-kilowatt little brother to the 50-kilowatt Iron Beam system, which is being developed to supplement the conventional Iron Dome anti-missile system.

Meanwhile, Russia has released a video purporting to show an HEL engaging a Ukrainian drone. The weapon looks identical to a Chinese-made Shen Nung, with an output of more than 30 kilowatts. Ukraine has also released footage of its 50-kilowatt Trident laser destroying drones in tests. Its commanders are eager to field Trident to defend against nightly waves of Iranian-designed Shahed drones fired from Russia.

Though trendy, HELs have drawbacks. Even though one blast is cheap, installing a system is not. The British Royal Navy’s Dragonfire HELs will cost £100m ($135m) apiece. Today’s lasers have relatively short ranges (of up to a few miles) and can be hampered by smoke, dust, haze or fog. In theory they can be carried around by planes or Jeeps, but get the power they need more easily from ships or on the ground. Lasers also have competition in the form of old-fashioned anti-aircraft guns, which are relatively cheap and can take on lots of targets. Attack drones are here to stay. The question is whether beams or bullets will blast them.■