Your comment focuses on what may or may not have been decrypted in time to inform US military leaders.
"The Myth of Pearl Harbor" does not depend on that argument at all. Instead, it focuses on what leaders like Roosevelt, Marshall and Churchill said and did in the months, weeks and days before December 7, 1941.
I'm satisfied that they fully expected a Japanese attack, and may even have known pretty well where and when.
By the way, the author George Victor is not ant-Roosevelt, far from it. He considers FDR a brilliant strategist, whose leadership brought victory in history's greatest war (55+ million dead) with a minimum cost in American lives.
My own opinion is that FDR deliberately "provoked" the Japanese by appearing weak while talking tough.
Again, I recommend the book. It may yet open your eyes and change your mind.
And how would they have done so without intel that would itself be a smoking gun?