In the mid-1990s and early 2000s, the U.S. military experimented with ground- and air-based chemical laser weapons. But they relied on a noxious batch of chemicals not found in the U.S. military logistics train. There were also bulky. The Airborne Laser had six magazines, each the size of an SUV, and could only get off 20-40 shots before depleting its chemical stores.

Ultimately, U.S. commanders felt that chemical lasers would burden a mobile force. By contrast, some Israelis were eager to try them against mortar shells and Qassam rockets from Gaza. Fans of Northrop Grumman’s NOC +1.07% Tactical High-Energy Laser lobbied hard in the press for a laser alternative to Iron Dome, which began development in 2007. But the missile-interceptor idea had the backing of the Israeli government, and the first Iron Dome battery was deployed in 2011.

The system performed well in 2012 and again during the current round of fighting with Hamas. Its Tamir interceptor is expensive ($40,000-$100,000), but a rocket crashing into downtown Beersheba is costlier. And Iron Dome conserves ammunition by only shooting down projectiles bound for populated areas.