I agree that FDR wanted to enter the war, and needed a reason that would independently bring along the American public, but I don’t think that included allowing Pearl Harbor.
Like 9-11, there were rumblings about attacks but that is standard before major military engagements.
For example, during that very time, there was sufficient information of an impending German attack on (1) France and (2) Russia. Both times the Germans succeeded brilliantly? Did Chamberlain and Stalin deliberately allow these to happen?
No. What is does validate is that “warnings” and “alerts” are part of standard chatter, and possibly part of standard disinformation, prior to invasion or attack.
About the best we can do is grieve that no one in intelligence put 2 and 2 together more quickly, to avert Pearl Harbor, or 9-11.
That’s another reason why FDR didn’t know. If he had, then he would have let the attack take place but would have had the military at least on alert. FDR was not an American-hating treasonous b-stard like so many American leftists today.
Also, if he wanted to enter the European war, why would he encourage an attack by Japan? If he was trying to create a Gulf of Tonkin incident it might better have been to send an American troopship to England with “observers” and let a German U-boat sink it. Losing a few hundred lives and a single ship is something a nefarious President might do; losing an entire fleet, having a harbor destroyed, and losing 3,000 lives is NOT something any rational person would do.
[Except perhaps Stalin, who sacrificed his entire professional officers corp in the name of the revolution. This is long considered the reason why he was so unable to stop Hitler.]
“Also, if he wanted to enter the European war, why would he encourage an attack by Japan? “
We had already sunk a couple of German ships off of the east coast prior to Pearl Harbor. But Hitler wouldn’t take the bait, he wouldn’t declare war on the U.S.