American Military History, Volume 2 by Richard W. Stewart

The United States did not return to its prewar isolationism after World War II. The balance of power in Europe and Asia and the safety of ocean distances east and west that made isolation possible had vanished: the war upset the balance, and advances in air transportation and weaponry surpassed the protection of the oceans. There was now little inclination to dispute the essential rightness of the position Woodrow Wilson espoused after World War I that the nations of the world were interdependent, the peace indivisible. Indeed, in the years immediately following World War II, full participation in world events became a governing dynamic of American life.

With the end of the war, American hopes for a peaceful future fo- cused on the United Nations (UN) formed at San Francisco in 1945. The fifty countries signing the UN Charter agreed to employ "effec- tive collective measures for the prevention and removal of threats to the peace and for the suppression of acts of aggression," including the use of armed force if necessary. The organization included a bicam- eral legislature: the General Assembly, in which all member nations had representation and a smaller Security Council. The latter had authority to determine when the peace was threatened, to decide what action to take, and to call on member states to furnish military formations. Five founding members of the United Nations (the United States, the Union of Soviet Socialist Republics, the United Kingdom, China, and France) had permanent representation on the Security Council and the power of veto over any council action. Since the United Nations' effectiveness depended largely on the full cooperation of these countries, the primary objective of American foreign policy as the postwar era opened was to continue and strengthen the solidarity those nations had displayed dur- ing the war.