Took too long editing.
But I don’t think the USN would have been grateful to the IJN for the chance at an upgrade. It just doesn’t make sense for the USN or the president to deliberately put our entire Pacific battleship fleet at risk or even intentionally sacrifice it. Like someone else said, we could have simply left a token 2 or 3 ships and still had the same effect.
Well, dudes, it all come from not understanding Intel and 20/20 hindsight. Here is the way I explain it. Let us say you have a jig-saw puzzle in front of you. You onlyhave1/3 of the pieces, but they are in place and you have the box cover, with the complete picture. It is fairly easy to see then that this white stuff is clouds and not sheep grazing, and this red piece is part of the barn.
But that is not the way Intel works. Say instead you do have 1/3 of the right pieces- and hundreds of pieces more- some are from other puzzles and some are deliberately included to try and fool you. And there is no box cover. Then try and tell me what the fluffy white piece is.
That is exactly the problem of armchair theorizers. See, now we know the Japanese did attack Pearl Harbor. The armchair theorizers can discard all the false intel and the intel about other things, and are left with only the right pieces and they have the box cover.
Sure, the USA knew *something *was up- but when, where (most thought the Phillipines), and how were conjecture.
And, face it, in 1941, very few dudes really thought that Battleships were old school and Aricraft carriers would be the critical part they really were. So no one would suggest us losing our main battle fleet to keep a couple of “crummy scout ships.”
However, a recent special on Pearl has shown that even if the USA was on full alert, it only would have mean a few more Japanese planes shot down, and lots more of our pilots dying in the air. The Zero was that much better than the planes we had there, and we hadn’t even learned the tactics about how to combat the Zero with our planes then. It would have been a “turkey shoot”.
It is obvious in retrospect that Bush did have plenty of warnings about 9/11. BUT (and I am no defender of Bush or Rice for that matter) humans have a tendency to ignore such things until they are forcibly driven home (e.g. by the 9/11 attacks themselves). And a good thing too. If we responded to every threat, we would have no time or attention or energy left for getting on with our lives. What has happened since then has been to try to make us spend all our time responding to one kind of threat ignoring all others. Especially when we take an airplane.
The decryptions of Japanese codes and ciphers were an international effort, although the Americans had the most success. See a summary here.
Shelby
I don’t believe the above to be a fair assessment of the “Victory Plan”.
Factually, the author was a Major Wedemeyer (not General Wiedermeyer), though he became a General later. This webpage gives an analysis of the strategic assumptions of the plan.
http://www.ibiblio.org/hyperwar/USA/USA-Victory/USA-Victory-3.html
Here is a webpage that gives lots of good background on Wedemeyer. Most of what I have read of the conspiracy theorists about Wedemeyer are contradicted by the straight dope.
Exactly. All of the Pearl Harbor conspiracy theorists ignore the fact that FDR was a former assistant SecNav (as was his cousin, Theodore). FDR simply loved the Navy (he even suggested names for warships, without being asked). I don’t think he would ever have purposefully done anything to so badly endanger the Pacific Fleet, and particularly not at the very outset of war.
By late 1941, U.S. decision-makers strongly suspected a Japanese attack was in the offing, but they didn’t know where or when. They took inadequate steps to prepare, and missed signals that are obvious only in hindsight. We shouldn’t attribute to malice what is readily and reasonably attributable to inertia.
You forgot to mention that the pieces are printed on both sides 90 degrees out of phase. 
And that’s the case with a lot of attacks. There are very frequently clues and warnings that make sense when you put them together with the benefit of hindsight.
What thread was this? (No word in that “phrase” is longer than 3 letters, so I can’t search for it.)
Wedemeyer. That’s how it’s spelled. I was trying to find out the spelling of his last name and tried googling several variations - most of which obviously produced no results. Finally, I got a few hits on “Albert Wiedermeyer” so I figured that must be it.