When Germany invaded Russia in late June 1941, Japanese leaders debated whether to join their Axis ally and attack the Soviets—who had defeated Japanese troops along the northern border of Manchukuo in 1939—or proceed with plans to target European colonies in the Far East. They did not rule out invading Russia if the German advance on Moscow succeeded, but they saw more to be gained by seizing those Asian colonies and their resources, which they hoped to use to subdue China and sustain a vast empire they called the Greater East Asia Co-Prosperity Sphere. French Indochina and the Dutch East Indies were fairly easy targets, but the British would not yield Malaya and Burma without a fight, and their American