Issues: Biological and Chemical Weapons

Before and during World War II, Japan produced large quantities of chemical weapons, as did a number of other countries, including the United States, the Soviet Union, and Germany.  On a number of occasions, the Imperial Japanese Army used poison gases in combat in China and the Pacific theatre.  It is estimated that tens of thousands of Chinese servicemen and civilians were injured or killed as a result of these munitions. 

After Japan's surrender, the Japanese military disposed of the remaining stocks of chemical weapons in Japan and elsewhere.  Many of these were weapons were abandoned in China, especially close to the Soviet border.  Estimated to be between 700,000 and 2 million rounds, they continued to cause injuries to resident, including some cases leading to deaths. The governments of Japan and China have been working together to clean up these weapons according to the Chemical Weapons Convention (CWC). In recent years, Chinese victims of Japan's chemical weapons—both during and after the war--have filed lawsuits against the Japanese government for compensation. 

During the war, the Imperial Japanese Army also conducted secret chemical and biological weapon experiment on human beings.  Led by Lt. Gen. Ishii Shiro, Unit 731 of the Kwantung Army was the largest of all such programs. After the war, Ishii and his close associates reached a secret agreement with the U.S. government and provided research data in exchange for impunity from war crimes trial.

For Japanese Foreign Ministry site on disposal of abandoned chemical weapons, see