Regional defense organization (1955–77) comprising Australia, France, New Zealand, Pakistan, the Philippines, Thailand, Britain, and the U.S. It was founded as part of the Southeast Asia Collective Defense Treaty in order to protect the region from communism.
Vietnam, Cambodia, and Laos were not considered for membership, and other countries in the region preferred membership in the nonaligned movement . SEATO had no standing forces, but its members engaged in combined military exercises. Pakistan withdrew in 1968, and France suspended financial support in 1975. The organization was disbanded officially in 1977.