ENMOD came in response to environmental modifications made by the US during conflicts in Vietnam, Laos, and Cambodia in the 1960s and 70s. The US used massive spraying of chemical herbicides - the defoliants Agent Orange (2,4,5-T & 2,4-D) and others - to deprive its foes of both food supplies and shelter.15 In "Operation Popeye" the US also attempted to change weather patterns by seeding clouds in order to worsen monsoons in Laos and North Vietnam and thereby impede delivery of supplies to insurgents in South Vietnam