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How did the attack on Pearl Harbor lead the United States into World War II?

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Pearl Harbor attack A U.S. battleship sinking during the Pearl Harbor attack.

The attack on Pearl Harbor on December 7, 1941, served as the definitive catalyst that ended American isolationism and brought the United States into World War II.12

Prior to the attack, the United States had maintained a policy of neutrality, despite providing material support to the Allies through the Lend-Lease Act and engaging in an undeclared naval war against Germany in the Atlantic. Tensions with Japan had escalated due to U.S. embargoes on essential resources like oil and scrap metal, which were imposed in response to Japanese expansionism in Asia.13

The surprise aerial assault on the U.S. Pacific Fleet in Hawaii resulted in over 2,400 American deaths and devastated the battleship force. This act of aggression unified the previously divided American public, with 97% of citizens supporting a declaration of war. On December 8, 1941, Congress declared war on Japan. Shortly thereafter, on December 11, Germany and Italy declared war on the United States, prompting the U.S. to reciprocate and fully commit to the global conflict.13