During the early years of the Cold War, American foreign policy had made its first priority the effort to checkmate Soviet expansionism in Europe. The result of this European emphasis had been the declaration of the Truman Doctrine and containment policy in 1947. Yet starting with the Chinese Revolution in 1949 and the police action in Korea one year later, American policy makers turned their attention to the growth of Communism and the outbreak of wars of national liberation in the underdeveloped world. From the Truman administration on, the Communist-led Vietnamese revolution had worried diplomatic and political leaders in the United States. The result was a gradual increase in American aid and advice to the government of first Ngo Dinh Diem and later a series of military governments in South Vietnam, all intended to halt the advance of Communism in Southeast Asia. The unfortunate result was the alignment of the United States against the forces of nationalism, which since World War II had been fused with the Communist movement led by the charismatic patriotic leader Ho Chi Minh.