The commanders and political systems that decide the crisis

Nagumo's instructions favor withdrawal if surprise is lost, while Yamamoto remains able to recall the force before Tokyo's political leadership resolves the crisis. American carrier commanders have broad authority to react to threatening conduct. Congress holds the power to declare war, while Roosevelt has more political freedom to respond to a Japanese threat than to a German one. The Japanese side is complicated by Tojo's expansive reading of imperial approval and Hirohito's indirect style of rule. Kimmel could prepare his fleet and use credible reconnaissance to secure Army cooperation on defensive measures outside his own chain of command.