Imagine that the US knew the Kido Butai was steaming toward Japan. Imagine the discussion then.
“Do we just let it happen and lose a big part of our fleet?”
“Sure, we can do that, it would start us off with a major disadvantage, but we’d be in the war. True, we’d be in the WRONG war, fighting the Japanese in what amounts to a distraction in the war against the Nazis, but what the heck, we’re too stupid to see that thwarting a sneak attack would be much better than trying to explain why eight battleships are on the bottom the next day.”
“Good thinking! Then we could declare war on Japan, but not on Germany. That way Germany would have to decide if we were at war with them. I’m sure Hitler will be daft enough to do that for us, so there’s no need to declare war against the entire Axis.”
This is what people think happened then? Really? REALLY?