Thor was the free world's first operational intermediate range ballistic missile (IRBM). The missile utilized a single stage North American Rocketdyne LR-79 liquid oxygen rocket motor. This gave the Thor of range of 2,000 miles. The Thor's 2,000 mile range was too limited for launching from the United States, so it essentially turned the deployment over to the United Kingdom. In early 1958, the two countries entered into an agreement whereby the US would furnish the missiles and train the RAF launch crews and the United Kingdom would build four Thor missile bases and man them with RAF missile squadrons.
