In 1957, the US Navy began using submarines in the nuclear deterrent role, when a pair of World War II vintage diesel-electric boats, and , converted to be able to carry a pair of
Regulus cruise missiles, began operating deterrent patrols. These two were soon joined by a
pair of purpose built diesel boats, and a nuclear powered boat, . However, the use of Regulus in the deterrent role showed a number of limitations; as a
cruise missile, it was vulnerable to interception by fighter aircraft, it was limited to
subsonic speed, and had a range of less than 1000 km, while the largest of the Regulus armed boats could carry a maximum of five missiles. Additionally, the submarine had to surface to launch a missile, and the missile was guided by a radio signal transmitted from either ship, aircraft or ground station. To overcome these limitations, the Navy turned to
ballistic missiles. The commissioning of
George Washington on 30 December 1959, the first submarine Polaris launch on 20 July 1960, and her first deterrent patrol November 1960 – January 1961 were the culmination of four years of intense effort. The Navy initially worked on a sea-based variant of the
US Army Jupiter intermediate-range ballistic missile, projecting four of the large, liquid-fueled missiles per submarine. Rear Admiral
W. F. "Red" Raborn was appointed by
Chief of Naval Operations Admiral
Arleigh Burke to head a Special Project Office to develop Jupiter for the Navy, beginning in late 1955. However, at the
Project Nobska submarine warfare conference in 1956, physicist
Edward Teller stated that a compact one-megaton warhead could be produced for the relatively small, solid-fueled
Polaris missile, and this prompted the Navy to leave the Jupiter program in December of that year. Soon Admiral Burke concentrated all Navy strategic research on Polaris, still under Admiral Raborn's Special Project Office. By comparison, the contemporary
Soviet and ballistic missile submarines only carried three missiles each; the Soviets did not commission an SSBN comparable to the
George Washington class until 1967 with the introduction of the s. ==Construction==