The
Southeast Asia Treaty Organization (
SEATO) was an
international organization for
collective defense in
Southeast Asia created by the
Southeast Asia Collective Defense Treaty, or
Manila Pact, signed in September 1954 in
Manila,
Philippines. The formal institution of SEATO was established on 19 February 1955 at a meeting of treaty partners in
Bangkok, Thailand The organization's headquarters were also in Bangkok. Eight members joined the organization.