The Douglas GAM-87A Skybolt was an air-launche ballistic missile (ALBM) developed during the late 1950s. It was intended to provide a mobile basing for the USAF's ICBM missile force by mounting them on heavy bombers rather than in fixed missile silos. A series of test failures and the development of submarine launched ballistic missiles (SLBMs) eventually led to its cancellation in the mid-1960s.