What event officially drew the United States out of isolationism and into World War II?

The event that officially drew the United States out of isolationism and into World War II was the attack on Pearl Harbor. This surprise military strike by the Japanese Imperial Navy on December 7, 1941, led to significant loss of life and damage to the U.S. Pacific Fleet. It galvanized public opinion in the United States, which had largely been isolationist and was hesitant to enter the conflict. Following the attack, President Franklin D. Roosevelt asked Congress for a declaration of war against Japan, which was granted on December 8, 1941. This event marked a turning point in the U.S. approach to international conflict, as it transitioned from a stance of neutrality to active involvement in World War II, ultimately leading to the broader engagement of U.S. forces against the Axis powers.