Not be all conspiracy theory and all.
I know that before December 7, 1941 the opinion of the American populace was not to engage in WW2 (I think only ~ 12% supported any engagement). I also know that Churchill was begging Roosevelt for support since by 1941 Britain was barely holding on (Russia eventually took the pressure off).
Roosevelt knew that US had to do something or else Nazism would spread like wild fire, but without support of it's people he could not do anything. So is there any possibility that a blind eye was cast on any Japanese attack?
The US (at least in naval circles) had a very strong appreciation for the abilities of the IJN. They had spent 25 years planning a war against them through the versions of War Plan Orange. Though that did not prevent inset racism and other assumptions from causing them to be underestimated in certain areas such as night fighting and the capabilities of their aircraft.
The Navy had a strong sense that war was coming, but fully expected it to begin in the Philippines and did not truly have an appreciation for the power of a massed task force of carriers and their striking power as the US had rarely even had 2 together where as the Pearl Harbor attack force had 6.