Japan and weapons of mass destruction

Beginning in the mid-1930s, the nation of Japan conducted numerous attempts to acquire and develop weapons of mass destruction. The 1943 Battle of Changde saw Japanese use of both bioweapons and chemical weapons, and the Japanese conducted a serious, though futile, nuclear weapon program. After the end of World War II the nation was forced to cease all production and abandoned their experiments.

Since World War II, Japan has become a nuclear-capable state, said to be a "screwdrivers turn" away from nuclear weapons, having the capacity, the know-how, and the materials to make a nuclear bomb. Japan has consistently eschewed any desire to have nuclear weapons, and no mainstream Japanese party has ever advocated acquisition of nuclear weapons or any weapons of mass destruction. Such weapons are forbidden by the Japanese constitution.

During the Sino-Japanese War (1937–1945) and World War II, Unit 731 and other Special Research Units of the Imperial Japanese Army conducted human experimentation on thousands, mostly Chinese, Korean, Russian, American, and other nationalities as well as some Japanese criminals from the Japanese mainlands. In military campaigns, the Japanese army used biological weapons on Chinese soldiers and civilians.

This employment was largely viewed as ineffective, due to inefficient delivery systems. However, information has surfaced in the last decade, which alleges a more active Japanese usage. For example, firsthand accounts testify the Japanese infected civilians through the distribution of plague-infested foodstuffs, such as dumplings and vegetables.

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