Which of the events was most influential in bringing the US into the world war 2?

The most influential event that brought the U.S. into World War II was the Japanese attack on Pearl Harbor on December 7, 1941. This surprise military strike led to significant loss of life and damage to the U.S. Pacific Fleet, galvanizing public opinion in favor of entering the war. In response, President Franklin D. Roosevelt asked Congress for a declaration of war against Japan, which was granted the following day, marking the U.S.'s formal entry into the global conflict.