Unit 731 (Japanese: 731部隊, Hepburn: Nana-san-ichi Butai), short for Manchu Detachment 731 and also known as the Kamo Detachment and the Ishii Unit, was a covert biological and chemical warfare research and development unit of the Imperial Japanese Army that engaged in lethal human experimentation and biological weapons manufacturing during the Second Sino-Japanese War (1937–1945) and World War II. Estimates vary as to how many were killed. Between 1936 and 1945, roughly 14,000 victims were murdered in Unit 731. It is estimated that at least 300,000 individuals have died due to infectious illnesses caused by the activities of Unit 731 and its affiliated research facilities. It was based in the Pingfang district of Harbin, the largest city in the Japanese puppet state of Manchukuo (now Northeast China) and had active branch offices throughout China and Southeast Asia.