Defoliation bacilli bombs , made between 1932 and 1933 were used by the Imperial Japanese Army to spread bubonic plague across China . The deployment of these lethal munitions provided the Japanese with the ability to launch devastating biological attacks , infecting agriculture , reservoirs , wells and populated areas with anthrax , plague-infected fleas , typhoid , dysentery and cholera . The alumni of Unit 731 , the unit that prepared these weapons , became top bioweapons researchers and were not prosecuted as war criminals . According to Richard Drayton , a Cambridge University history lecturer , researcher Shirō Ishii later moved to Maryland , where he conducted research into bioweapons . However , according to Ishii 's daughter Harumi , he stayed in Japan , where he died of throat cancer at the age of 67
Unit 731
Unit 731
Defoliation bacilli bomb