There is no debate that FDR did send out "War Warnings" to all commanders in late November 1941.
These warnings mentioned the possibility of sudden Japanese attack in places like the Philippines and Singapore.
But there was no mention of Hawaii, nor had there been any specific warnings beyond sabotage to Hawaii's commanders.
As for background: any good history book -- including Homer's posts here -- clearly show FDR slowly tightening the screws, poking at the Japanese, and making demands on them (i.e., withdrawal from China) which he knew were impossible for Japan to meet.
What most of those books leave out are the "whys" of FDR's actions, and to learn those you have to turn to more controversial books, of which several have been frequently mentioned here.
Of course, those who wish to defend FDR's innocence vigorously attack such books, and even more their authors.
So it's still a big debate.
But I think there are a large number of data-points which when we "connect the dots", tell us that the President's inner circle and top intelligence people knew or suspected more than they let their commanders in Hawaii in on.
btw, speaking of what FDR knew, just got done reading “in the garden of beasts”, its the true story of the ambassador FDR sent to berlin in 1933. that guy clearly called it 5 years in advance and told fdr repeatedly that the Nazi’s were absolutely insane, fully intended to start a big war, and were killing jews. apparantly FDR was one of the few people who believed the guy.
highly reccomend the book for any WW2 history buff. well written.
bonus material: the ambasadors daugher had numerous affairs with nazi’s and communists which are all well detailed.