The Americans were first attacked by the Japanese Empire at Pearl Harbor.
The Attack on Pearl Harbor constituted a surprise military attack perpetrated by the Imperial Japanese Navy Air Service upon the United States against the naval base at Pearl Harbor in Honolulu, Hawaii on Sunday morning, December 7, 1941. As a consequence of this attack. the United States' formally entered into World War II the next day. The attack initiated at 7:48 a.m. Hawaiian Time.