Before Roosevelt's second term was well under way, his domestic program was overshadowed by a new danger little noted by average Americans: the expansionist designs of totalitarian regimes in Japan, Italy and Germany. In 1931 Japan invaded Manchuria and crushed Chinese resistance; a year later the Japanese set up the puppet state of Manchukuo. Italy, having succumbed to fascism, enlarged its boundaries in Libya and in 1935 attacked Ethiopia. Germany, where Adolf Hitler had organized the National Socialist Party and seized the reins of government in 1933, reoccupied the Rhineland and undertook large-scale rearmament.  

As the real nature of totalitarianism became clear, and as Germany, Italy and Japan continued their aggression, American apprehension fueled isolationist sentiment. In 1938, after Hitler had incorporated Austria into the German Reich, his demands for the Sudetenland of Czechoslovakia made war seem possible at any moment in Europe. The United States, disillusioned by the failure of the crusade for democracy in World War I, announced that in no circumstances could any country involved in the conflict look to it for aid. Neutrality legislation, enacted piecemeal from 1935 to 1937, prohibited trade with or credit to any of the warring nations. The objective was to prevent, at almost any cost, the involvement of the United States in a non-American war.  

With the Nazi assault on Poland in 1939 and the outbreak of World War II, isolationist sentiment increased, even though Americans were far from neutral in their feelings about world events. Public sentiment clearly favored the victims of Hitler's aggression and supported the Allied powers that stood in opposition to German expansion. Under the circumstances, however, Roosevelt could only wait until public opinion regarding U.S. involvement was altered by events.  

With the fall of France and the air war against Britain in 1940, the debate intensified between those who favored aiding the democracies and the isolationists, organized around the America First Committee, whose support ranged from Midwestern conservatives to left-leaning pacifists. In the end, the interventionist argument won a protracted public debate, aided in large measure by the work of the Committee to Defend America by Aiding the Allies.  

The United States joined Canada in a Mutual Board of Defense, and aligned with the Latin American republics in extending collective protection to the nations in the Western Hemisphere. Congress, confronted with the mounting crisis, voted immense sums for rearmament, and in September 1940 passed the first peacetime conscription bill ever enacted in the United States -- albeit by a margin of one vote in the House of Representatives. In early 1941 Congress approved the Lend-Lease Program, which enabled President Roosevelt to transfer arms and equipment to any nation (notably Great Britain, the Soviet Union and China) deemed vital to the defense of the United States. Total Lend-Lease aid by war's end amounted to more than $50,000 million.  

The 1940 presidential election campaign demonstrated that the isolationists, while vocal, commanded relatively few followers nationally. Roosevelt's Republican opponent, Wendell Wilkie, lacked a compelling issue since he supported the president's foreign policy, and also agreed with a large part of Roosevelt's domestic program. Thus the November election yielded another majority for Roosevelt. For the first time in U.S. history, a president was elected to a third term.