Why the U.S. Couldn't Stay NEUTRAL in World War II [APUSH Review]

After World War I, the U.S. adopted a foreign policy that promoted world order while advocating for isolationism. The desire for a "return to normalcy" and to avoid future conflicts led to the passage of Neutrality Acts between 1935 and 1937, making foreign entanglements difficult. The Nye Committee's investigation suggested that bankers and war manufacturers profited from WWI, fueling public isolationist sentiment, despite questionable evidence.

Despite the push for isolationism, the U.S. remained involved in international affairs to promote a world order favorable to its interests. This occurred through financial investments like the Dawes Plan (1924), which provided loans to Germany to pay reparations, thus stabilizing the European economy and centering global finance on the U.S. However, the Great Depression's effects halted this system.

The U.S. also influenced world affairs by signing international peace treaties, such as the Kellogg-Briand Pact (1928), which nominally renounced war but lacked enforcement mechanisms, allowing the U.S. to appear engaged without military obligations. Additionally, selective military interventions, primarily in Latin America (e.g., the occupation of Haiti from 1915-1934), were driven by the Roosevelt Corollary and dollar diplomacy to protect American economic interests and align these nations with U.S. foreign policy.

As World War II began, the tension between isolationism and global engagement continued. The rise of fascism in Germany under Hitler and aggressive expansionism by Japan (e.g., invasion of Manchuria in 1931) strained U.S. neutrality. The fall of France to the Nazis in 1940 further pushed Roosevelt to assist Great Britain without declaring war through policies like "cash and carry" and later the "Lend-Lease Act." These actions, including naval patrols against German submarines, created an undeclared naval war.

The surprise Japanese attack on Pearl Harbor on December 7, 1941, killed over 2,400 Americans and destroyed significant naval assets. This event dramatically shifted American public opinion, ending isolationist sentiments. Roosevelt requested and received a declaration of war against Japan, and four days later, Germany and Italy declared war on the U.S. due to their alliance with Japan, formally drawing the United States into World War II to combat fascism and totalitarianism.