The biggest question is whether or not the B-21 will be unmanned. Strategic bombers are, after all, built so they can carry nuclear weapons if need be, as well as other, less-apocalyptic payloads. In late 2014, Popular Science spoke with a senior defense official at the Pentagon involved in the program, who insisted that, when carrying a nuclear weapon, the bomber will have a human crew on board. The B-21's Ace Combat 2-style concept art seems to confirm that, with windows visible on the plane. This matches the ad Northrop Grumman aired during the Super Bowl this year, which put cockpits for human pilots on their future fighters.