Thor was the first operational ballistic missile in the arsenal of the United States. Thor was 65 feet (19.8 m) in height and 8 feet (2.4 m) in diameter. It was deployed in the UK between 1959 and 1963 as an Intermediate Range Ballistic Missile (IRBM) with thermonuclear warheads. It was later augmented in the U.S. IRBM arsenal by the PGM-19 Jupiter.
A large family of space launch vehicles -- the Delta rockets -- were derived from the Thor design. Its descendants fly to this day as the Delta II and Delta IV rockets.