The Southeast Asia Collective Defense Treaty was signed in Manila on September 8, 1954, as part of the American Truman Doctrine on the creation of anti-communist and bilateral and collective defense treaties.  These treaties and agreements should create alliances that would keep the communist powers in check (Communist China, in the case of SEATO).  This policy was developed largely by the American diplomat and Soviet expert George F. Kennan. President Dwight D. Eisenhowers, Secretary of State John Foster Dulles (1953-1959), is considered the main force behind the creation of SEATO, which extended the concept of collective anti-communist defense to Southeast Asia.  On his return from his trip to Asia in late 1953, Richard Nixon favored an Asian equivalent of the North Atlantic Treaty Organization (NATO), and NATO was the model for the new organization, with each member`s forces to be coordinated to ensure the collective defense of member states.  After its creation, SEATO quickly became militarily insignificant, as most of its member countries contributed very little to the alliance.  While seato`s armed forces underwency in joint military training, they were never deployed due to internal differences. SEATO was unable to intervene in the conflicts in Laos because France and the United Kingdom refused to resort to military action.
 As a result, the United States unilaterally rejected Laos after 1962.  Although sought by the United States, SEATO`s participation in the Vietnam War was rejected due to a lack of British and French cooperation.   The signatories, including France, Great Britain, Australia, New Zealand, the Philippines, Pakistan, Thailand and the United States, pledged to “act to address the common danger” in the event of aggression against a signatory state. A separate protocol to SEATO designated Laos, Cambodia and “the free territory under the jurisdiction of the State of Vietnam [southern Vietnam]” as territories also subject to the provisions of the treaty. The contractual language did not go as far as the absolute reciprocal defence commitments and military structure of the NATO Alliance, but only provided for consultations in the event of aggression against a signatory state or a protocol state before combined actions were taken. This lack of agreement that would have forced a military response combined with the aggression significantly weakened SEATO as a military alliance. However, it was used as the legal basis for US`s engagement in southern Vietnam. SEATO expired on 30 June 1977.
New Zealand was one of the 51 United Nations that, by signing the Charter of the United Nations in June 1945, ensured its support for the principle of collective security. This was seen as an important way to ensure that small nations had a voice in world politics.