By 2015, the Missile Defense Agency had started efforts to deploy a laser on a high-altitude UAV. Rather than a manned jetliner containing chemical fuels flying at , firing a megawatt laser from a range of "tens of kilometers" at a boost-phase missile, the new concept envisioned an unmanned aircraft carrying an electric laser flying at , firing the same power level at targets potentially up to "hundreds of kilometers" away for survivability against air defenses. While the ABL's laser required to generate one kW, the MDA wanted to reduce that to per kW, totaling for a megawatt. Unlike the ABL, which required its crew to rest and chemical fuel to be reloaded, an electric laser would need only power generating from fuel to fire, so a UAV with in-flight refueling could have near-inexhaustible endurance and armament. A "low-power demonstrator" has been planned to fly sometime in or around 2021.