Yes, hostilites were possible. That doesn’t mean FDR knew anything. Any time you can no longer negotiate with a militaristic power you must prepare for hostilities.
Where is the evidence that FDR knew something that he failed to pass on to our fighting men for their preparedness?
Again, I’m not arguing Roosevelt held anything back, just that the Japanese attack was the reasonable person’s expected outcome of the situation.
I refer you again to The Pearl Harbor Myth, to fill in the blanks of what you don't know.
It is 303 pages long, filled with data & quotes.
Quoting from page 42:
"Victor Cavendish-Bentinck, chair of Britain's Joint Intelligence Committee (JIC) in 1941, wrote years later about the Japanese fleet that attacked Pearl Harbor:
"We knew that they changed course. I remember presiding over a J.I.C. meeting [on December 5, 1941] and being told that a Japanese fleet was sailing in the direction of Hawaii, asking 'Have we informed our transatlantic brethren?' and receiving an affirmative reply... [We had given] the US authorities...ample time to at least send most of the fleet out of Pearl Harbor.""