Special Landing Force Alpha was officially designated as the 31st Marine Amphibious Unit (MAU) on 24 November 1970. Once more the unit returned to the Gulf of Tonkin. This time, however, the 31st MAU would not be committed to overt land operations as the Vietnam War was winding down. The 31st MAU performed presence missions and conducted a series of special operations through May 1971. From June 1971 until April 1975, the 31st MAU conducted many deployments to the waters off Vietnam.