The SSM-N-2 Triton was a supersonic nuclear land-attack cruise missile project for the United States Navy. It was in development from 1946 to 1957, but probably no prototypes were produced or tested. The Triton program was approved in September 1946, designated SSM-2 a year later, and redesignated SSM-N-2 in early 1948. A preliminary design was produced by 1950 as the XSSM-N-2, but was scaled down by 1955 and redesigned again in 1957. Triton was cancelled in 1957, probably as a result of the 1956 decision to focus the Navy's strategic weapons development on the Polaris submarine-launched ballistic missile. In any case, prototypes of the similar Regulus II missile had already flown, and Triton was redundant, offering only an increase in range from 1,000 to 1,500 nautical miles, which Polaris was about to achieve along with many other advantages. Regulus II was itself cancelled in 1958, although testing of missiles already built continued for several years.