The B-1B Lancer is a supersonic variable-sweep wing , heavy bomber used by the United States Air Force . It is commonly called the "Bone" (from "B-One") due to its distinctive shape . The aircraft is capable of reaching Mach 1.25, and can fly at high subsonic speeds at low altitudes for extended periods of time. It is equipped with an advanced avionics suite and the capability to carry a wide range of air-launched weapons. The B-1B is designed to penetrate enemy defenses and deliver both conventional and nuclear weapons. It is also used for long-range surveillance and reconnaissance missions.