75 years ago 2,403 Americans were killed in the Japanese surprise attack on Pearl Harbor, Hawaii Territory. The attack caused the United States to officially enter World War II. The attack was carried out by Japan as a preventative measure to stop the US Pacific Fleet from interfering with Japanese war efforts in Southeast Asia. Following the attack on Pearl Harbor, Japan also attacked US-held Philippines, Guam, and Wake Island. Roosevelt described the attack the following day, saying, “Yesterday, December 7, 1941 – a date which will live in infamy – the United States of America was suddenly and deliberately attacked by naval and air forces of the Empire of Japan.”December 7 officially became a day of remembrance recognized by Congress on August 23, 1994, but not a federal holiday. It is observed by lowering the flag to half-staff. Here are powerful photos of the aftermath of the attack.