A 1950s report published in Peking by an international commission concluded that the U.S. used bioweapons on North Korea. The report raised doubts about claims that captured Americans were brainwashed into confessing the use of such weapons.

Chinese film of 1953, purporting to show soldiers (?) in white body suits in Korea. Chinese scientists testing reactions to chemical spraying. Biological warfare.

However, documents acquired in the 1990s from the former Soviet Union concluded that the accusations of United States use of biological weapons during the Korean conflict were fraudulent.

Former USSR – World Atlas

Biological warfare in a historical perspective – A review by R.Roffey, A.Tegnell, F.Elgh

During World War I Germany infected horses being shipped to the Allies with anthrax or glanders

During World War II the USA, Russia, the UK, Canada, France, Italy, Germany, Japan, and Hungary tried to acquire biological weapons capability but use was limited. In contrast, the Japanese biological weapons program became advanced with the production of plague, anthrax, typhoid, cholera and dysentery agents tested on prisoners of war and used against Chinese populations. 

In 1943, work on biological warfare agents began at Fort Detrick, Maryland. The US program during WWII developed small-particle-size aerosol dissemination of wet or dry preparations of pathogens and a production facility for bacterial agents was opened in the Pine Bluff Arsenal in Arkansas. At its peak in the 1950-60s, the program involved a number of agents including: Bacillus anthracis, Francisella tularensis, Brucella suis, Coxiella burnetti, Venezuelan equine encephalitis (VEE) virus, yellow fever, botulin, staphylococcal enterotoxin, and the anti-crop agents Pyricularia oryzae and Puccinia graminis.

In 1969 the U.S. joined the Biological and Toxin Weapons Convention, agreeing to stop further offensive biological weapons development and to use the facilities for peaceful purposes or for bio-defense work only. In 1992 Russia banned ongoing biological weapons development. But concerns still exist regarding possible residual programs and U.S.intelligence reports suggest several states (e.g., Iran, North Korea, Syria) still have active programs.