Operation McLain (also known as Operation Dan Thang) was a security operation conducted during the Vietnam War by the U.S. Army’s 3rd Battalion, 506th Infantry Regiment, 101st Airborne Division and the Army of the Republic of Vietnam (ARVN) 44th Regiment, 23rd Division in Bình Thuận Province, South Vietnam from 20 January 1968 to 31 January 1969.