I agree with the general premise that FDR knew an attack was imminent and will add, so did the Army and Navy, but I was struck by this wiki source so I had to look at it a bit closer. The first statement that says that intelligence stated that Pearl Harbor was going to be attacked is incorrect if referenced to its own source. The source which is an article by Thomas Fleming states that there was a lot of signs that the Japanese were going to attack but does not give any specifics to exactly where. And Thomas is right. FDR did know we were going to be attacked, but not necessarily at Pearl. The intel at the time had reports of a fleet leaving Shanghai headed south which led them to think that the Philippines was the target....which it was. They did not have intel of the fleet headed to Pearl and even if they were reading every scrap of JN-25 it wouldn't have enlightened them to that fleet because they were under radio silence. Now according to Crane Files there was no JN-25 traffic being read at all in the months prior to Pearl Harbor, so the assertion that the CIA is withholding information is likely bogus and stands to reason why it says [citation needed]. This is why I never cite Wikipedia. It is a good place to get a jump off point for further research, but more often than I would like the details in their write ups leave something to be desired.
You are correct. If you read the newspapers from late 1941 it is blindingly obvious that war is coming between Japan and the West. The only question was “when”?
That is why we were building up the Philippines as fast as we could. The Dutch and the British were doing the same.
Pearl Harbor was a one off raid. It was important, but it did not determine US participation in the war.