The Manchurian Incident (1931), the establishment of a puppet state in Manchuria (19329, and the decision to leave the League of Nations (1933) changed Japan’s international trajectory. In the 1920s, Japan had been a pillar of international collaboration and multilateralism. Now it was an aggressive outsider. International condemnation of Japan’s war in China (1931-1945) and the accompanying sanctions seemed to threaten Japan’s national security. In response, Japan attacked the United States in December 1941, hoping to drive the Americans out of the Pacific long enough to secure resources for a self-sufficient empire. This did not turn out well.