For a brief period during the Vietnam War, Convair F-102 Delta Daggers were used in the night ground attack role- the infrared equipment designed to track Soviet bombers was used to detect Viet Cong activity in the jungles of South Vietnam. Pilots soon became adept at identifying insurgent campfires and even tracking someone smoking a cigarette. An IR missile intended for air-to-air engagements would be fired at the heat source, sometimes resulting in secondary explosions.
With the arrival of increasing number of F-4 Phantoms in theater, the ground attack role of the F-102 was short lived.
Source: Combat Aircraft, October-November 2008. "Century Series: F-102 Delta Dagger" by Warren E. Thompson, p72.