Which factors were key in US involvement in World War II?

• A. Japanese attack on Pearl Harbor in 1941 and the global rise of totalitarian regimes, along with alliance commitments
• B. Discovery of vast oil reserves in the Pacific
• C. Domestic political scandals and isolationist sentiment
• D. Unrest in Latin America and economic recession

Answer: (A)

The key idea is that the United States entered World War II because of a direct threat and a broader, mounting challenge from totalitarian powers, supported by its alliance commitments. The immediate catalyst was the Japanese attack on Pearl Harbor in 1941, which showed that American soil and security could be directly attacked and made war a necessity. At the same time, the global rise of totalitarian regimes in Europe and Asia threatened democratic countries and free trade, pushing the U.S. to shift from helping allies to actively joining the fight. The U.S. had already begun aiding Allies through measures like Lend-Lease, signaling a move toward full involvement, and its alliance obligations with Britain, the Soviet Union, and others created a framework for collective security. Other factors, such as discoveries of oil, domestic scandals, isolationist sentiment, or unrest in Latin America, did not provide the same clear, compelling push to enter the war.