Answer: it's main goal was to stop communism (diminish aggression)
SEATO is an international organization for collective defense in southeast Asia created by the southeast Asia signed in September 1954. The formal institution of SEATO was established in Philippines in 1955. One of the steps that is take by US to diminish aggression in Southeast Asia and to preserve peace and freedom is to join Southeast Asia treaty organization popular known as SEATO. SEATO is a collective security organization among eight nations (United States, France, Great Britain, New Zealand, Australia, the Philippines, Thailand and Pakistan)