Air interdiction, by contrast, attacks tactical targets that are distant from or otherwise not in contact with friendly units.
It began in the Italo-Turkish War when pilots dropped small bombs over the side of their open cockpits onto enemy troops below.
By the time of World War II a number of specialized aircraft were developed to fulfill this role, including various fighter-bombers.
During the Korean War tactical bombing missions were sometimes carried out by older piston-powered fighters such as the Vought F4U Corsair.
In the Vietnam War, missions were frequently directed by Forward air controllers (FACs) flying small propeller-driven planes.