ISOLATIONISM

At end of WWI America retreated into isolationism, they wanted to stay away from European affairs. The U.S. hoped WWI would be the "war to end all wars" , the Kellogg-Briand Pact was agreed a pond by almost all nations pledging not to use military forces  for aggressive reasons. These ideas weren't not only naive but they were unrealistic. In 1939 war broke out in Europe and despite their claim to isolationism in 1941 America joined the fight in WWII.