I've always been on the fence on this one.
As far as the navel codes go, I agree that they were broken, but they weren't broken by the Americans. It was the British that had them broken. We all know how badly Churchill wanted the Americans in the war, and what a Machiavellian slime he was.
Added to that, it doesn't take a genius to know that he wouldn't have let the bulk of the US fleet get nailed, Churchill would have known what the most important parts of the US Pacific fleet are. The remaining question is, would he have shared with Roosevelt the information, or would he have had up to the minute intel that the attack was coming and would he have shared it? But there is no argument, the allies knew the attack was coming, the only argument, is whether they had told FDR.
Who can say. I'm sure the allies must have known an attack was coming though. . . probably they were intending the Japanese to hit the Philippians first.
Capt. Eric Nave, 94; Broke Japan's Code Before Pearl Harbor
Capt. Eric Nave, 94; Broke Japan's Code Before Pearl Harbor