Correct me if i'm wrong, but from what i can understand, the Japanese strategy regarding the US was that if they can inflict a crushing and demoralizing defeat upon the US the American civilians would lose the will to continue fighting and quickly sued for peace, like what happened to Russia in 1905.
Obviously, this did not happen, but what if it did? What if the US, after the attack on Pearl Harbour, backs off from Japan's ambition on the Pacific?
One effect i could see is that FDR would quickly get thrown out of the White House if this were to happen, but what about Japan? What would they do now?