Operation Ranch Hand was a U.S. Military operation during the Vietnam War; lasting from 1962 until 1971. It was part of the overall herbicidal warfare program during the war called 'Operation Trail Dust'. Ranch Hand involved spraying an estimated 20 million US gallons of defoliants and herbicides over rural areas of South Vietnam in an attempt to deprive the NLF (Viet Cong) of vegetation cover and food. Areas of Laos and Cambodia were also sprayed to a lesser extent. Nearly 20,000 sorties were flown between 1961 and 1971.