Newly released archival documents offer detailed insight into the Imperial Japanese Army’s chemical warfare activities in China during the Second Sino-Japanese War, highlighting the role of Unit 516, a key Japanese chemical weapons research and deployment unit.
The evidence emerged from registration files of the Kwantung Army Chemical Department, known as Unit 516, which was established in 1939 in Qiqihar, Heilongjiang province. The unit was primarily responsible for developing and employing chemical weapons, including nerve agents, blister agents, choking agents, and irritants, as part of Japan’s broader biological and chemical warfare program during the conflict.
The documents, recently made public by the Exhibition Hall of Evidences of Crime Committed by Unit 731 in Harbin, were initially compiled by former members of Unit 516 upon their return to Japan after World War II. The records, which cover 148 pages and include detailed information on 108 personnel, were transferred to the National Archives of Japan in 2000 and declassified gradually over time. These files were obtained following a 2023 research mission to Japan involving extensive searches and discussions.
According to Jin Shicheng, director of education and publicity at the museum, the registration files contain comprehensive biographical and military service data, such as names, places of origin, family details, ranks, service branches, deployment dates, disarmament locations, and postwar experiences. Jin noted that while the original Unit 516 was established with around 250 personnel, subsequent research expanded the known roster to 505 individuals after consolidation with other records, due in part to transfers and temporary assignments during the war.
The documents also provide further evidence of collaboration among Units 516, 731, and 100—organizations implicated in biochemical warfare crimes during Japan’s occupation of China. The files notably include information about Hiroshi Kusunoki, a former Unit 516 member who underwent veterinary training at Unit 100, underscoring personnel exchanges and cooperation between the groups.
Prior investigations and war crime confessions have established that these units collectively conducted poison gas experiments and other chemical warfare operations targeting humans, animals, and the environment. The newly released records reinforce this understanding by charting the organizational structure, personnel movements, and coordinated nature of the activities.
The exhibition’s organizers emphasize that the documents provide critical new evidence to better comprehend the scale and systematic nature of Japan’s wartime chemical weapons program, framing it as a large-scale and top-down orchestrated campaign. Further research is anticipated to expand the historical record of Unit 516 and related entities.