When it enters service, the B-21 will replace the USAF's B-2 Spirit bombers.
Both the B-2 Spirit and B-21 Raider "flying wings" are subsonic American strategic bombers designed to avoid radar and be capable of delivering conventional and thermonuclear weapons. American defense giant Northrop Grumman built both; at first glance, the aircraft look nearly identical. However, the B-21 Raider is slightly smaller, features a longer range, and has far more advanced technology than the B-2 it will replace.