Developed from the Huey transport helicopter, the Cobra was the first purpose-built helicopter gunship to enter military service. It was the mainstay of U.S. Army attack aviation from its combat debut in South Vietnam during 1967 until replaced by the AH-64 Apache in the 1980s and `90s. Versions of the Cobra continue to serve in the U.S. Marine Corps and the armed forces of many nations.