Designed as a supersonic superiority fighter, the Lockheed F-104 Starfighter was produced in two major versions. Armed with a six-barrel M-61 20mm Vulcan cannon, it served as a tactical fighter, and when equipped additionally with heat-seeking Sidewinder missiles, as a day-night interceptor. More than 1,700 F-104s were built in the United States and abroad under the military aid program for various nations including Canada, West Germany, Italy, Norway, the Netherlands, Belgium, Denmark, Greece, Turkey, Spain, Taiwan and Japan.