 It was during this period of intense combat that Special Landing Force Alpha earned the Presidential Unit Citation.The unit participated in continuing combat operations ashore over the next three years, including the Vietnam Tet counteroffensive in 1969, while returning to Okinawa periodically for re-outfitting and the rotation of forces.Special Landing Force Alpha was officially designated as the 31st Marine Amphibious Unit (MAU) on 24 November 1970.