Vietnamization, 1969-1973 President Richard Nixon's Vietnamization policy implemented a phased withdrawal of American ground forces and their replacement by South Vietnamese troops. However, the USAF continued supplying critical air support. Tactical air power became a key part of the Allied incursions into communist sanctuaries in Cambodia in 1970. Moreover, USAF strike aircraft, gunships and B-52s helped stop the enemy's 1972 Easter Offensive into South Vietnam. Click here to return to the Close Air Support index. Find Out More Related Fact Sheets South Vietnam: The Easter Offensive Note: The appearance of hyperlinks does not constitute endorsement by the National Museum of the USAF, the U.S. Air Force, or the Department of Defense, of the external website, or the information, products or services contained therein.