From what I have read FDR etal did not have the actionable intelligence—but it is likely Winston Churchill did—and refused to share since he needed the US in the war.
The British had impressive code-breaking capability (far better than the US)—but it is hard to prove they broke the relevant Japanese codes at that time.
This is not a part of their history the Brits want us to know about...
This is not a part of their history the Brits want us to know about...
Not the Brits. The Soviets, Richard Sorge tipped them of that Japan was going south.