The United States officially entered World War II on December 8, 1941, the day after the Japanese attack on Pearl Harbor on December 7, 1941. On December 8, President Franklin D. Roosevelt delivered his famous "Day of Infamy" speech to Congress, which then declared war on Japan. Subsequently, on December 11, 1941, Nazi Germany and Italy, allies of Japan, declared war on the United States, and the U.S. declared war on them as well, fully entering the global conflict in both the Pacific and European theaters.