From 1965 to 1971 the United States Marines in Vietnam ran a small, little-known operation called the 'Combined Action Program.' In many ways what CAP did was similar to what was done by the US Army Special Forces, the famous Green Berets, except the Marines concentrated most of their effort in the heavily populated coastal lowlands rather than the sparcely populated highlands. Most CAP units consisted of a Marine rifle squad and US Navy Medical Corpsman, and a Vietnamese Popular Forces platoon