On the foreign policy front, the National Government embedded New Zealand in a series of Western Cold War security alliances and defence agreements. In September 1951, the government signed the ANZUS defence agreement with Australia and the United States. As a member of the Western alliance, the National Government also sent New Zealand troops to the Korean War. A demand for woollen clothing during the conflict created a brief economic boom for New Zealand's sheep farmers. In September 1954, New Zealand ratified the Manila Pact and joined the Southeast Asia Treaty Organization, an American-sponsored regional collective defense organization aimed at combating the spread of Communism in Southeast Asia. Later, in January 1955, New Zealand's traditional ties to Britain and a fear of the Communist domino effect led Prime Minister Holland to contribute New Zealand troops to the Malayan Emergency. According to the historian David McIntyre, Holland had little interest in foreign affairs and was the first Prime Minister to delegate that portfolio to another cabinet minister. During the Holland era, New Zealand had three foreign ministers: Frederick Doidge, Clifton Webb, and Tom Macdonald.