A defence agreement between Japan and the USA. Negotiated as part of the package of arrangements attending the formal return of Japanese independence after defeat in World War II, the treaty established the USA as the effective arbiter of Japan’s defence interests, granting it a large military presence in Japanese territory. Renewal of the treaty in 1960, as a Mutual Security Treaty, with revised terms, produced a major political crisis in Japan: when renewal next became due in 1970, both countries agreed to a process of automatic extension on the condition that revocation could be achieved on one year’s notice by either.