In the late 1950’s a new threat emerged from the Soviet Union for which the Americans were seemingly caught off guard. The latest generation of Soviet nuclear-powered submarines could reach incredible speeds. The Alfa-Class submarine under development at the time would eventually be capable of travelling at 41 knots (76 kph/47 mph) while fully submerged. At such speeds, these submarines could follow American fleets while easily evading ASW ships. Large, fast, ocean-going hydrofoils seemed like the answer.