The Republic F-105 Thunderchief is an American fighter-bomber that served with the United States Air Force from 1958 to 1984. Capable of Mach 2, it conducted the majority of strike bombing missions during the early years of the Vietnam War. It was originally designed as a single-seat, nuclear-attack aircraft; a two-seat Wild Weasel version was later developed for the specialized Suppression of Enemy Air Defenses (SEAD) role against surface-to-air missile sites. The F-105 was commonly known as the "Thud" by its crews. It is the only American aircraft to have been removed from combat due to high loss rates.