The United States began Operation Steel Tiger over the Laos Panhandle and the DMZ on 3 April 1965, to locate and destroy enemy forces and materiel being moved southward at night into South Vietnam, and to fly bomb damage assessment reconnaissance runs over targets attacked in the secret war the United States fought there. These flights teamed with B-57B bombers operating out of Bien Hoa Air Base and a C-130 Hercules flare ship. Three more aircraft were subsequently modified in 1964/65 bringing the number of aircraft to five.