1) Japan had ambitions of expanding its empire across Asia to gain resources and influence, conquering parts of China but facing economic struggles due to lack of materials like oil. 2) Tensions rose between Japan and the United States as America imposed embargoes on trade with Japan, leading Japan's military leaders to decide to attack the U.S. Pacific fleet at Pearl Harbor on December 7, 1941 in an attempt to prevent American interference with their expansion. 3) After Pearl Harbor, Japan rapidly conquered territories across the Pacific and Southeast Asia over the next few months, but their advance was stopped at the Battle of Midway in June 1942 as the Allies began to turn the tide of the war in the Pacific.