Step-by-step explanation:
By mid-1941 the United States had severed all economic relations with Japan and was providing material and financial support to China. Japan had been at war with China since 1937, and the German invasion of the Soviet Union in June 1941 ensured that the Soviets were no longer a threat to the Japanese on the Asian mainland. The Japanese believed that once the U.S. Pacific Fleet was neutralized, all of Southeast Asia would be open for conquest.