I have read several books where it is 'suggested' Roosevelt was aware of the impending attack.
It's worth bearing in mind that 1941 was not 2019 with bad hairstyles. The entire nature of intelligence, military intelligence and capabilities were nothing like we have today. So the definition of "aware" doesn't necessarily translate into the same damning indictment it would today.
It's most likely a shoeshine boy in Arkansas might have been "aware" of Japanese intentions. We in the UK seem to forget a bit too easilty that the US has two massive seaboards to worry about, and these days we don't feature in one of them (by design, by the way. So much for the "special relationship").
However doing something with that awareness in an age without satellites, reliable aerial reconnaissance, integrated communications, and immediate response would have been a challenge at best.
The fact that more USians believe the Moon Hoax bollocks than believe Roosevelt sold them down the river is instructive.
I could quite believe Churchill could have hidden the "truth" though - but even then, if you have thousands of cables a day floating across your desk, and there are a few - ultimately contradictory ones which hint there might be an attack somewhere in the Pacific sometime in the next few days, what are you to do with it apart from put it with the others.
Forget enormous naval fleets, our own MI5 who are equipped with high-tech out the wazzo (although expenses are still paper based ...) managed to lose track of 4 potential targets who were merely ambling around on land in Britain.
Military Intelligence very often isn't.