The Senate's repudiation of the Treaty of Versailles following World War I is often seen as ushering in a period of isolationism in American foreign policy. It was impossible for the United States to withdraw completely from world affairs, however, because American possessions stretched from the Caribbean to the Pacific and because the First World War had transformed the country into the world's leading creditor nation. As the threat of war grew in the 1930s — with the rise of the Nazis in Germany and Japanese aggression in China — Congress tried to insulate the United States from potential hostilities through neutrality legislation. While public sentiment remained strongly in favor of staying out of a European conflict, isolationism became increasingly difficult after war broke out in Europe in September 1939.
Although the United States did not join the League of Nations, it did cooperate with international agencies throughout the 1920s and into the 1930s on such matters as trade and drug trafficking. The United States also headed efforts to advance diplomatic talks on limited disarmament, to resolve the tangled questions of war debts and reparations, and to maintain international peace, all while remaining deeply involved in Western Hemisphere affairs, particularly in Central America. American foreign policy was far from isolationist in the '20s.
