Japan's non-nuclear weapons policy

Japan's non-nuclear weapons policy is a policy popularly articulated as the Three Non-Nuclear Principles of non-possession, non-production, and non-introduction of nuclear weapons imposed by Douglas MacArthur during the Allied occupation of Japan following the Second World War.

Following World War II, the atomic bombings, at Hiroshima and Nagasaki and the deconstruction of their imperial military, Japan came under the US "nuclear umbrella" on the condition that they wouldn't produce nuclear weapons. The requirement was imposed by the United States that Japan might develop nuclear weapons, as the technology to develop a nuclear device became known around the world. This was formalized in the Security Treaty Between the United States and Japan, a corollary to the Treaty of Peace with Japan, which authorized the U.S. to deploy military forces in Japan in order "to contribute to the maintenance of the international peace and security in the Far East and to the security of Japan against armed attack from without". The treaty was first invoked in 1953 when, following a series of Japanese airspace violations by Soviet MiG-15s, the Japanese Foreign Ministry requested U.S. intervention.

In the years after the occupation, with the atomic bombings of Hiroshima and Nagasaki still fresh in the Japanese consciousness, public sentiment was strongly against the use, and even presence on Japanese soil, of nuclear weapons. This sentiment was evidenced by the widely reported accidental irradiation of the Daigo Fukuryu Maru from a U.S. hydrogen bomb test in 1954. News of the incident aroused public fears over radiation and outcry against atomic and nuclear weapons testing.

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