 Complete the following phrase:  The post-war era has seen limited, though devastating, use of chemical weapons. During the Vietnam War, between 1962 and 1971, the United States military sprayed nearly 20,000,000 U.S. gallons 76,000 m3 of various chemicals  the rainbow herbicides and defoliants  in Vietnam, eastern Laos, and parts of Cambodia as part of Operation Ranch Hand, reaching its peak from 1967 to 1969. Some 100,000 Iranian troops were casualties of Iraqi chemical weapons during the IranIraq War. Iraq used mustard gas and nerve agents against its own civilians in the 1988 