When the United States entered the war , mounting British pressure for the creation of a similar research program for an Allied pooling of resources led to the creation of a large industrial complex at Fort Detrick , Maryland in 1942 under the direction of George W. Merck . The biological and chemical weapons developed during that period were tested at the Dugway Proving Grounds in Utah . Soon there were facilities for the mass production of anthrax spores , brucellosis , and botulism toxins , although the war was over before these weapons could be of much operational use . However , the most notorious program of the period was run by the secret Imperial Japanese Army Unit 731 during the war , based at Pingfan in Manchuria and commanded by Lieutenant General Shirō Ishii . This unit did research on BW , conducted often fatal human experiments on prisoners , and produced biological weapons for combat use . Although the Japanese effort lacked the technological sophistication of the American or British programs , it far outstripped them in its widespread application and indiscriminate brutality . Biological weapons were used against both Chinese soldiers and civilians in several military campaigns . Three veterans of Unit 731 testified in a 1989 interview to the Asahi Shimbun that they contaminated the Horustein river with typhoid near the Soviet troops during the Battle of Khalkhin Gol . In 1940 , the Imperial Japanese Army Air Force bombed Ningbo with ceramic bombs full of fleas carrying the bubonic plague . A film showing this operation was seen by the imperial princes Tsuneyoshi Takeda and Takahito Mikasa during a screening made by mastermind Shiro Ishii . During the Khabarovsk War Crime Trials the accused , such as Major General Kiyashi Kawashima , testified that as early as 1941 some 40 members of Unit 731 air-dropped plague-contaminated fleas on Changde . These operations caused epidemic plague outbreaks
Unit 731
Unit 731
History of biological warfare