Beginning in 1962 during the Vietnam War, the Chemical Corps operated a program that would become known as Operation Ranch Hand. Ranch Hand was a herbicidal warfare program which used herbicides and defoliants such as Agent Orange. The chemicals were color-coded based on what compound they contained. The U.S. and its allies officially argued that herbicides and defoliants fall outside the definition of "chemical weapons", since these substances were not designed to asphyxiate or poison humans, but to destroy plants which provided cover or concealment to the enemy. The Chemical Corps continued to support the force through the use of incendiary weapons, such as napalm, and riot control measures, among other missions. As the war progressed into the late 1960s, public sentiment against the Chemical Corps increased because of the Army's continued use of herbicides, criticized in the press as being against the Geneva Protocol, napalm, and riot control agents.