1. The aftermath of World War I: The United States had suffered significant casualties and economic disruption during World War I, and there was a strong public sentiment against military intervention in Europe again.
2. Pacifism and anti-war sentiment: There was a strong pacifist movement in the United States after World War I, with many Americans believing that the war had been a pointless tragedy and that the United States should avoid future wars at all costs.
3. The Kellogg-Briand Pact: The Kellogg-Briand Pact of 1928, which outlawed war as an instrument of national policy, reinforced the isolationist sentiment in the United States and further discouraged the country from becoming involved in international conflicts.
4. America First Movement: The America First Movement, which became prominent in the late 1930s, advocated for the United States to remain neutral in World War II and to focus on its own economic and domestic issues.
5. Great Depression: The Great Depression, which began in 1929 and lasted throughout the 1930s, caused widespread economic hardship in the United States and made it difficult for the government to prioritize international affairs.