The Barracuda-class submarines (originally the K-1-class submarines) were the product of Project Kayo, a research and development effort begun immediately after World War II by the United States Navy to "solve the problem of using submarines to attack and destroy enemy submarines." They originally had the hull classification symbol SSK, for "hunter-killer submarine". It was known that the Soviet Navy had acquired the German Type XXI U-boat and other advanced submarines, and was expected to rapidly put derivatives of them into production. In 1948 the US Navy prepared estimates of the number of anti-submarine warfare (ASW)-capable submarines (SSKs) that would be needed to counter the hundreds of advanced Soviet submarines that were expected to be in service by 1960. Two scenarios were consid