The United States formally entered World War II after the attack on Pearl Harbor on December 7, 1941. This surprise military strike by the Japanese Empire targeted the U.S. naval base in Hawaii and resulted in significant losses in both personnel and military ships. The attack galvanized public opinion and led to a united call for action against Japan. Shortly thereafter, on December 8, 1941, President Franklin D. Roosevelt delivered his famous "Day of Infamy" speech and requested a declaration of war against Japan, marking the official entry of the U.S. into the global conflict.