I don't believe that for a second...the Pacific Ocean was alive with international shipping and air traffic...to think that the Japanese fleet could have crossed it without being detected is nonsense....Roosevelt wanted into that war and many pacificists in this country did not. Many of our most important allies were already involved and he knew that they were incapable of carrying the load....Our industrial power was, by far, the most formidable in the world and soon turned into a war machine.
Do you have any idea how much of the Pacific is virtually devoid of human presence, even more so back then? They specifically took a route which kept them away from the established shipping lanes and populated islands. They also enacted a complete communications lockdown, imposing radio silence on the strike force to the point of disabling radio transmitters on all but the planes of the strike leaders. They also had radio operators in home waters simulating the presence of the carriers. And could you please explain how allowing the attack to unfold would ensure war with Germany? Roosevelt has been called many things by many people, but I don’t think anyone ever truly thought he was stupid. Even if Roosevelt knew about it and wanted to let it happen to start a war, the near-annihilation of the Pacific Fleet wasn’t needed. The presence of the Kido Butai that close to Hawaii without any announcement was sufficient cause in itself for a declaration of war. The fleet could have been sent out for a night ambush, thereby turning the tables, or it could have been sent out of the harbor and out of the reach of the strike force. Bottom line, Roosevelt could have gotten his war without sacrificing multiple ships and several thousand men killed and wounded. Given that he was once the Assistant Secretary of the Navy and was a staunch supporter of the service throughout his life I’m rather hard put to believe that he would let its ships and men be sacrificed so needlessly. I guess that it’s easier and less galling to believe in a conspiracy than to accept that our forces were complacent, careless, and significantly underestimated their enemy.