USS Cusk was the first submarine to launch a missile from underwater, conducting the historic test in 1955.
Cusk was a United States Navy submarine converted to carry the guided Regulus missile. On 12 February 1955, it launched a Regulus from a submerged position off the California coast, proving that a submarine could release a large missile without first surfacing.
The Regulus was a turbojet-powered cruise missile designed to carry a nuclear warhead. Because it needed to be prepared on deck and launched from a surface position in later operations, it was not the same as a modern submarine-launched ballistic missile.
USS George Washington is often connected with an earlier milestone: in 1960 it became the first submarine to launch a ballistic missile from underwater. Cusk’s 1955 achievement involved a cruise missile instead.