This is a U.S. Air Force Atlas F intercontinental ballistic missile (ICBM), the last version made of this first ICBM in the U.S. nuclear arsenal. Deployed from 1962-1965, the liquid-fuel Atlas F used all-intertial guidance, carried a thermonuclear warhead, and had a range of over 7,000 miles. After being withdrawn from deployment, the missiles were refurbished and used for over twenty years as space launch vehicles. This Atlas F was transferred to the Smithsonian from the National Aeronautics and Space Administration in 1975.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.