The Rockwell (now part of Boeing) B-1 Lancer is a four-engine variable-sweep wing strategic bomber used by the United States Air Force (USAF). First envisioned in the 1960s as a supersonic bomber with sufficient range and payload to replace the Boeing B-52 Stratofortress, it developed primarily into a low-level penetrator with long range and supersonic speed capability at high altitude.

Designed by Rockwell International, the bomber's development was delayed multiple times over its history, as the theory of strategic balance changed from flexible response to mutually assured destruction and back again. This change in stance repeatedly demanded then ignored the need for manned bombers. The initial B-1A version was developed in the early 1970s, but its production was canceled, and only four prototypes were built. The need for a new platform once again surfaced in the early 1980s, and the aircraft resurfaced as the B-1B version with the focus on low-level penetration bombing. However by this point development of stealth technology was promising an aircraft of dramatically improved capability. Production went ahead as the B-1B would be operational before these "Advanced Technology Bomber" concepts, during a period when the B-52 would be increasingly vulnerable. It entered service in 1986 with the USAF Strategic Air Command as a nuclear bomber.