Agent orange The chemical weapon "Agent Orange" or 2,4,5-T (Acid 2,4,5-trichlorophenoxyacetic) is commonly mistaken for the herbicide 2.4-D, widely used in Brazil and worldwide. The "Agent Orange" was used by the armed forces of the United States of America for the defoliation of the rainforests where the Vietcong were sheltered, using the forest as a refuge, transportation route of supplies and etc.