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Who Used Mustard Gas in WWII?

By Brendan I. KoernerPosted Wednesday, Oct. 1, 2003, at 3:53 PM ET

A Tokyo court has awarded $1.7 million to 13 Chinese citizens who claim they were sickened by Japanese mustard gas left over from World War II. Did Japan actually use chemical weapons during the conflict?

Yes, although the extent of Japan's chemical warfare has never been resolved. What's known for sure is that the Japanese Imperial Army left behind thousands of tons of chemical weapons when it left China in 1945. Japan estimates that 700,000 such shells, bombs, and supply drums remain in the country, buried throughout its provinces; China puts the figure closer to 2 million. What's less clear is exactly when and where these weapons were used. The most well-documented instance occurred in 1941 at Yichang, a city in the central province of Hubei. The Japanese reportedly used mustard gas and lewisite when seizing the city and again to repel the Chinese Nationalist troops who attempted to recapture it. Additionally, Japan's infamous Unit 731, a covert biological warfare program, tested chemical weapons on thousands of Chinese citizens.

A current historical exhibition near Beijing, sponsored by the Chinese government, claims that Japan used chemical weapons 2,000 times between 1937 and 1945, resulting in 100,000 Chinese casualties. Japan's Foreign Ministry has never countered with its own enumeration, preferring to remain mum on the subject of actual battlefield deployments. Such an admission would amount to a formal acknowledgement that Japan violated the Geneva Protocol of 1925, which banned the use of chemical weapons. Other violators have included Iraq, which deployed gas against both Iran and the Kurds, and Italy, which conquered Ethiopia in the 1930s with the aid of mustard gas.

Japan has, however, acknowledged the prevalence of its abandoned chemical weapons beneath Chinese soil. Those weapons have repeatedly injured unwitting Chinese citizens over the past 58 years, most recently in August when one person was killed and at least 40 injured in the northeast town of Qiqihar. A group of construction workers accidentally unearthed several drums of mustard gas and cut them up to sell as scrap.

As a signatory to the Chemical Weapons Convention, which took effect in 1997, Japan must remove all of its abandoned chemical arms from China within 10 years. The country also has some residual issues to deal with on the home front, too. In May, residents of a town near Tokyo fell ill after drinking from an arsenic-laden well. Investigators concluded that the toxin had seeped out of barrels manufactured by the nation's chemical-weapons program. The buried barrels have yet to be located.

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Explainer thanks the Federation of American Scientists.

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Brendan I. Koerner is a contributing editor at Wired and a columnist for Gizmodo. His first book, Now the Hell Will Start, is out now.
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