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U. S. DEMANDS EXPLANATION OF JAPAN MOVES - AMERICANS PREPARE FOR ANY EMERGENCY; NAVY DECLARED READY - Hawaiian newspaper headline
"1. Military transport (name unknown) departed for mainland on 2nd. 2. Luline arrived from San Francisco on 3rd." - R.C.A. coded traffic from Honolulu to Tokyo
"Judging from all indications, we feel that some joint military action between Great Britain and the United States, with or without a declaration of war, is a definite certainty in the event of an occupation of Thailand." - Message from Washington to Tokyo transmitted in Purple code. Translated on December 5th
"Wyoming and two seaplane tenders departed third." - R.C.A. coded traffic from Honolulu to Tokyo
British intelligence in Manila sends an urgent cable to British intelligence in Hawaii saying: We have received considerable intelligence confirming following developments in Indo-China. A. 1. Accelerated Japanese preparations of air fields and railways. 2. Arrival since Nov. 10 of additional 100,000 repeat 100,000 troops and considerable quantities fighters, medium bombers, tanks and guns (75 mm). B. Estimate of specific quantities have already been telegraphed Washington Nov. 21 by American military intelligence here. C. Our considered opinion concludes that Japan envisages early hostilities with Britain and U.S. Japan does not repeat not intend to attack Russia at present but will act in South.
Colonel Bicknell is shown by Rochefort the first message from the Navy Department in Washington reporting that the Japanese were destroying their codes and secret papers.
The two war warning messages, both concerning the destruction of the Japanese codes and code machines were sent by OPNAV to CINCAF, COM16 (Hart), COM14 (Bloch), and CINCPAC (Kimmel). The first one reads: HIGHLY RELIABLE INFORMATION HAS BEEN RECEIVED THAT CATEGORIC AND URGENT INSTRUCTIONS WERE SENT YESTERDAY TO JAPANESE DIPLOMATIC AND CONSULAR POSTS AT HONGKONG, SINGAPORE, BATAVIA, MANILA, WASHINGTON, AND LONDON TO DESTROY MOST OF THEIR CODES AND CIPHERS AT ONCE AND TO BURN ALL OTHER IMPORTANT CONFIDENTIAL AND SECRET DOCUMENTS. The second message read: CIRCULAR TWENTY FOUR FORTY FOUR FROM TOKYO ONE DECEMBER ORDERED LONDON, HONGKONG, SINGAPORE, AND MANILA TO DESTROY MACHINE. BATAVIA MACHINE ALREADY SENT TO TOKYO. DECEMBER SECOND WASHINGTON ALSO DIRECTED DESTROY, ALL BUT ONE COPY OF OTHER SYSTEMS, AND ALL SECRET DOCUMENTS. BRITISH ADMIRALTY LONDON TODAY REPORTS EMBASSY LONDON HAS COMPLIED.
These two messages alone should are the single most important ones sent to the fleets in both the Philippines and Pearl Harbor. The Japanese destruction of their codes are a sure indication that full scale war is immanent.

HIGHLY RELIABLE INFORMATION HAS BEEN RECEIVED THAT CATEGORIC AND URGENT INSTRUCTIONS WERE SENT YESTERDAY TO JAPANESE DIPLOMATIC AND CONSULAR POSTS AT HONGKONG, SINGAPORE, BATAVIA, MANILA, WASHINGTON, AND LONDON TO DESTROY MOST OF THEIR CODES AND CIPHERS AT ONCE AND TO BURN ALL OTHER IMPORTANT CONFIDENTIAL AND SECRET DOCUMENTS.

But not Honolulu.

more than that, the Hawaii Command gets intel that the Hawaiin Japanese embassy is burning large amounts of papers.

Also, the FBI has Japanese locals phones tapped and records converations between them and Japan which are clearly suspected of being reports on ship movements and presence in the Harbor.

Again, no one puts the pieces together largely because of a total lack of imagination: Kimmel and Short just flat out refused to believe the Japanese had the capability and the daring to raid Pearl.