isolationism, a national policy of abstaining from political, military, or economic alliances or agreements with other countries. Isolationism may be adopted in order to devote a country's energies to becoming self-sufficient or addressing domestic problems, or sometimes to contain foreign influence. Many countries have had policies of isolationism at one time, including China, Japan, Albania, Paraguay, and North Korea.
Political and military isolationism has been a recurring sentiment in the United States, beginning with George Washington's Farewell Address in 1796, in which he warned the young nation against becoming involved in European politics and wars. The aspects of isolationism inform the Monroe Doctrine (1823), which opposed European intervention in the Western Hemisphere, especially in Latin America, and stated that the United States would not interfere in European affairs. The country's reluctant participation in World War I marked a departure from its former policy, but the losses suffered in war and the failure of Woodrow Wilson's internationalism caused public opinion to once more turn against foreign entanglements, and contributed to the U.S. rejection of the League of Nations.
Isolationism again became a popular political stance in the 1920s and 30s. The Neutrality Act of 1935 was a reaction to the American public's fear of being involved in another costly war. The Great Depression also caused Americans to turn their concerns inward during this time. A strong noninterventionist lobby, led by the America First Committee and its popular spokesman Charles Lindbergh, was able to keep the United States from entering World War II until the Japanese bombing of Pearl Harbor in 1941. President Franklin Roosevelt and other U.S. leaders subsequently supported establishing the United Nations and America's active participation in it. After the war, the rise of the Soviet Union and its sphere of influence (and strong U.S. opposition to that), improved communication and transportion, increased world trade, and other changes made it impossible for the United States to again cut itself off from the rest of the world.
See S. Dunn, 1940: FDR, Wilkie, Lindbergh, Hitler—The Election amid the Storm (2013); L. Olson, Those Angry Days: Roosevelt, Lindbergh, and America's Fight over World War II, 1939–1941 (2013).