World War II involved Japan.
Attack on Pearl Harbor . The attack , also known as the Battle of Pearl Harbor , led to the United States ' entry into World War II . Axis powers . The Axis grew out of the diplomatic efforts of Germany , Italy and Japan to secure their own specific expansionist interests in the mid-1930s . World War II . In December 1941 , Japan attacked the United States and European colonies in the Pacific Ocean , and quickly conquered much of the Western Pacific .