Emerging revelations unveil the grim details of Japan's infamous biological warfare operations during World War II.
A network of units, spanning from Unit 731 in northern China to Unit 8604 in Guangzhou and Unit 9420 in Singapore, has been uncovered, shedding light on Japan's biological warfare activities during World War II.
The recent release of declassified documents by the Russian Federal Security Service (FSB) in August 2025 has fuelled renewed scholarly and public attention on this dark chapter of history. These documents provide further evidence and details about Unit 731's biological warfare activities and human experimentation.
Historically, Unit 731, based in Harbin, northeast China, was infamous for deliberate infection experiments on prisoners of war and civilians. They cultivated pathogens such as plague bacteria and conducted field trials that dispersed disease vectors via ceramic bombs filled with infected fleas and contaminated water and food supplies. These actions led to massive civilian casualties and extensive disease outbreaks.
The release of these documents coincides with ongoing efforts by researchers, such as those at Meiji Gakuin University's International Peace Research Institute, to further document and analyse the full scope of Unit 731's activities. The documents have been used in exhibitions and legal/historical presentations by political figures and researchers in Japan, China, and elsewhere, contributing to increased discourse on wartime accountability and ethical violations in human experimentation.
However, full official investigations remain limited. This is partly due to many Unit 731 members being granted immunity after the war in exchange for their data being shared with U.S. forces, leading to restricted disclosure and political sensitivity around the issue.
One of the last eyewitnesses able and willing to speak about Unit 731 is 95-year-old Hideo Shimizu, who joined the Youth Corps at age 14 and arrived at unit headquarters in 1945. Shimizu remembers being led into a room filled with specimens of human organs in glass jars as the most shocking thing he experienced.
Despite a Tokyo court ruling in 2002 that the military had conducted such experiments and waged biological warfare, Japan's government has never officially apologised for Unit 731's actions. This year, a film about Japan's inhumane medical experiments during WWII, titled 731 Biochemical Revelations, was postponed without explanation, causing an online outcry.
Meanwhile, Japan's national archives made public Unit 1644's personnel rosters at the request of researchers in May. Each unit "tried to adapt to local conditions, solving problems in the environment they were fighting in, and using them against their enemy." With euphemistic names such as "anti-epidemic and water supply" units, their job was to keep their own troops healthy, while getting their enemies sick, by spreading diseases such as plague and malaria.
Lv Jing, a historian at Nanjing University, believes the rosters will enable researchers to better understand the structure of Japan's germ warfare system. The release of these documents has boosted research into Japan's germ warfare program, which lasted from 1936 to 1945.
Despite the historical significance, full transparency and justice remain constrained by historical post-war politics. It is hoped that continued research and public discourse will bring greater understanding and accountability for these atrocities committed during World War II.
- The newfound documents, released by the Russian Federal Security Service in August 2025, have sparked renewed interest in Japan's biological warfare activities during World War II, specifically involving Unit 731, as they provide further evidence and details about the unit's environmental manipulations and human experimentation.
- The release of documents related to Japan's germ warfare program, including Unit 731's activities, has been instrumental in political discussions and scholarly analysis, as evidenced by the use of these documents in exhibitions, legal/historical presentations, and ongoing research initiatives.
- As the government of Japan has yet to officially apologize for Unit 731's actions, there remains a call for increased transparency and accountability in the ongoing investigation and discussion of these atrocities committed during World War II, especially as new documents come to light, such as the recent release of Unit 1644's personnel rosters.
