対米覚書
This is the content of the investigation report of diplomatic shame that MOFA finally disclosed on Nov. 20th 1994, about what "elite" bureaucrats really did or did not do for the "sneak attack."
窶「 Tokyo started transmitting the instruction at 6:30am EST on Dec. 6th 1941 to the embassy in Washington DC. It said that the war declaration equivalent ("memorandum" technically speaking) was to be fragmented into 14 encrypted telegrams.
窶「 13 telegrams followed, they went through by 3pm, Dec. 6th.
窶「 The 14th part, which also meant to be the go-ahead sign, was sent at 2am, Dec. 7th.
窶「 The final instruction marked urgent (sent at 3:30am Dec. 7th) told the ambassador Kichisaburo Nomura to hand the document at 1pm EST Dec. 7th, preferrably to the secretary of state Cordell Hull directly.
窶「 Telegrams were to be first deciphered, the 14 document parts needed to be officially typed up. Tokyo specified the secretary officer, not typists, to do the second part for the security reasons.
窶「 There was plenty of time, no rush for typing the short 14th part for delivery to Department of State by 1pm either. In fact the first 13 parts were all decoded by 8pm Dec. 6th, ready for typing.
窶「 What happened was: the only person in the embassy at that time who was authorized for type-up, First Secretary Katsuzo Okumura, went out to attend a coworker secretary Hidenari Terasaki's farewell party at a Chinese restaurant. Okumura was playing card games after the party, with others instead of returning. Councillor Sadao Iguchi told staff to go home, although the telegram department chief Masana Horiuchi wanted to stay. There was no one with decipher skills there early in the Sunday morning of Dec. 7th.
窶「 That was how they missed the most important deadline for the nation. They say it was 55 minutes after IJN bombed the naval base in Pearl Harbor as planned, when Hull received it. MOFA kept telling that everything was an entry-level employee's fault. Iguchi was promoted to vice foreign minister on Jan. 30th 1951. Okumura became the vice foreign minister on Oct. 17th 1952.
For more background, consequence and accuracy, read
Between Incompetence and Culpability by Seishiro Sugihara.
Just bad, although US already was capable of decrypting Purple.