Following the use of poison gases used in World War 1, the 1925 Geneva Protocol that prohibited the use of chemical and biological weapons in war was created. The Protocol was drawn up and signed at a conference which was held in Geneva under the auspices of the League of Nations from May 4, 1925 to June 17, 1925, and it entered into force on 8 February 1928. [2, 3]
Protocol for the Prohibition of the Use in War of Asphyxiating, Poisonous or Other Gases, and of Bacteriological Methods of Warfare – commonly refered to as The Geneva Protocol
It took 50 years for the US to ratify this convention (1975) the same year they ratified the Biological and Toxins Weapons Convention (BTWC). During the 50 year span the US used chemical (napalm, agent orange) and likely biological weapons in Korean and Vietnam wars. [1]