What pivotal event led the United States to enter World War II?

Question

Japan’s attack on Pearl Harbor
Japan’s takeover of China
Japan’s attack on Midway Island
Japan’s takeover of Southeast Asia

Answer 1

The pivotal event that led the United States to enter World War II was Japan’s attack on Pearl Harbor. This attack occurred on December 7, 1941, and resulted in significant losses for the U.S. Pacific Fleet, prompting the United States to formally declare war on Japan the following day.