The Japanese leadership, including the military and Emperor Hirohito, was very much divided over questions of military expansion and engaging the U.S. in warfare. Hirohito frequently expressed his desire that diplomacy supercede any planning for war, but as supreme commander of the armed forces he had to ensure the survival of Japan and in the end it was a combination of dysfunctional politics and jingoistic advisors that pushed the acquiescent emperor to approve a war plan that a more assertive leader could have vetoed.
Japan 1941: Countdown to Infamy
by Eri Hotta
Knopf, 2013
Out of the Past
1941: Attack on Pearl Harbor
History and American West Titles