by DAVID KAHN
On December 2, after only two days of analyzing the new calls, Rochefort’s unit stated in its Communications Intelligence Summary: “Carriers—Almost a complete blank of information of the Carriers today. Lack of identifications has somewhat promoted this lack of information. However, since over two hundred service calls have been partially identified since the change on the first of December and not one carrier call has been recovered, it is evident that carrier traffic is at a low ebb.” In the next day’s summary appeared the last mention of carriers before December 7, and it was rather negative: “No information on submarines or carriers.”
Other messages, however, clearly indicated the drive to the south, which Japan made no attempt to conceal. Twice before, Rochefort, Fabian, Layton, and O.N.I. had seen exactly the same conditions, and twice before their reasoning that the carriers were being held in empire waters had been proved right. Now, they thought, they were seeing it happen again. Temporarily oblivious to the possibility of a surprise attack on Pearl Harbor, they watched the forces moving against Malaya as hypnotically as a conjuror’s audience stares at the empty right hand while the left is pulling the ace out of a sleeve.
American preconceptions were reinforced by two PURPLE messages of December 1, which the Navy read that same day. In the first, Tokyo directed Washington: “When you are faced with the necessity of destroying codes, get in touch with the naval attaché’s office there and make use of chemicals they have on hand for this purpose. The attaché should have been advised by the Navy Ministry regarding this.” Five days earlier, the cryptanalysts had read Tokyo’s detailed instructions on how to destroy the PURPLE machine in an emergency. These two code-destruction messages appeared to be just precautionary measures in a tense situation, and this impression was strengthened by the second message of December 1. It seemed to virtually announce a Japanese invasion of British and Dutch possessions and to relegate conflict with the United States to a subsequent date: “The four offices in London, Hongkong, Singapore and Manila have been instructed to abandon the use of the code machines and to dispose of them. The machine in Batavia has been returned to Japan. Regardless of the contents of my circular message #2447 [which MAGIC did not have], the U.S. (office) retains the machines and the machine codes.” American officials breathed easier. The messages appeared to give the United States a bit more of what it needed most—time, time to build up its pitifully weak Army and Navy.
While the world gazed with tunnel vision toward Southeast Asia, and American radio intelligence envisioned the Japanese carriers in home waters, six of them—Akagi, Kaga, Hiryu, Soryu, Shokaku, and Zuikaku—were in fact butting eastward through the high winds and waves of the vacant sea. Late in the afternoon of December 2, Tokyo time, the force picked up, apparently on a blanket broadcast, an electrifying open-code message intended for it: NIITAKA-YAMA NOBORE (“Climb Mount Niitaka”). It informed the strike force that the decision for war had been made and directed it to Proceed with attack. Niitaka-yama, also known as Mount Morrison, is a peak on Formosa whose 12,956-foot elevation made it the highest point of what was then the Japanese empire. The symbolism could not have been lost on the officers. The force refueled from its tankers.
There was trouble in Honolulu. The F.B.I. had, early in November, begun to tap the telephone of the manager of an important Japanese firm in the hope of obtaining some clues to possible espionage activity. The tap was in addition to those placed on the Japanese consulate by Mayfield, who was helped by an employee of the telephone company whom the 14th Naval District Intelligence Office had cultivated as its contact. Unexpectedly, however, a telephone repairman came across the jumper wire that the F.B.I. had put across the connections in the junction box. The Navy’s contact man immediately tipped off Mayfield’s office, which warned the F.B.I.—who promptly complained to the telephone company that their confidence had been breached. Mayfield, fearful that the commotion would disclose his own telephone surveillances and that such disclosure would give the Japanese an excuse for almost any action, pulled his taps. His recording operator jotted a wistful farewell under his final notes. “At 4 p.m. Honolulu time in the 1941st year of Our Lord, December 2 inst., I bade my adieu to you my friend of 22 months standing. Darn if I won’t miss you!! Requiescat in Peace.” The F.B.I., however, maintained its other taps.
Earlier that day, the consulate had received Circular #2445 in J19, relayed by Washington from Tokyo:
Take great pains that this does not leak out.
You are to take the following measures immediately:
1. With the exception of one copy each of the o [PA-K2] and the L [LA] codes, you are to burn all telegraph codes (this includes the codebooks for communication between the three departments [HATO] and those for use by the Navy).
2. As soon as you have completed this operation, wire the one word HARUNA.
3. Burn all secret records of incoming and outgoing telegrams.
4. Taking care not to arouse outside suspicion, dispose of all secret documents in the same way.
Since these measures are in preparation for an emergency, keep this within your consulate and carry out your duties with calmness and care.
The codes were duly burned, including the TSU, or J19, in which the circular was transmitted. That evening Kita sent HARUNA. Henceforth the consulate code secretary, Samon Tsukikawa, would have to transmit the spy messages of Yoshikawa, alias Morimura, in the simpler PA-K2.
The first such message arranged four signaling systems by which a spy might report on the condition of the ships in Pearl Harbor. The arrangement had been submitted to Yoshikawa by an Axis spy in Hawaii, Bernhard Julius Otto Kühn. Nazi Propaganda Minister Josef Goebbels had transferred him to the islands in 1935 after a contretemps with Kühn’s daughter Ruth, who had become Goebbels’ mistress when she was 16. In his signaling system, Kühn stipulated that numbers from 1 to 8 would mean such things as A number of carriers preparing to sortie (which was 2) and Several carriers departed between 4th and 6th (which was 7). Then he arranged that bonfires, house lights shown at certain times and places, or want ads broadcast over radio station KGMG would mean certain numbers. For example, 7 would be represented by two lights shown in the window of a house on Lanikai Beach between 2 and 3 a.m., or by two sheets between 10 and 11 a.m., by lights in the attic window of a house in Kalama between 11 and 12 p.m., or by a want ad offering a complete chicken farm for sale and listing P.O. Box 1476. If all these failed, a bonfire on a certain peak of Maui Island between 8 and 9 p.m. would indicate 7. The purpose of the system was to eliminate dangerous personal contacts between Kühn and the Japanese. Kühn tested it on December 2, found that it worked, and passed it to Yoshikawa. He had it encoded (in PA-K2) and sent to Tokyo in two long parts on December 3.
It was now the third day of the month in which the Japanese consulate gave its cable business to R.C.A. Following Sarnoff’s instructions, George Street, district manager of the firm, had had the Japanese consulate messages copied on a blank sheet of paper with no identification of the sender or addressee. About 10 or 11 a.m., December 3, Mayfield called at the branch office and Street slipped him a blank envelope containing the messages. As soon as Mayfield returned to the District Intelligence Office, he had a messenger bring them down to Rochefort.
In Washington that Wednesday, the Signal Intelligence Service solved a PURPLE message from Tokyo—and the readers of MAGIC, who only two days earlier had been lulled by the supposition that Japan might temporarily spare the United States, were stunned by the realization that the arrow of war might be loosed momentarily. For the message ordered the Washington embassy to “burn all [codes] but those now used with the machine and one copy each of o code [PA-K2] and abbreviating code [LA]…. Stop at once using one code machine unit and destroy it completely … wire … HARUNA.” Under Secretary of State Welles saw it and felt that “the chances had diminished from one in a thousand to one in a million that war could then be avoided.” When the President’s naval aide, Beardall, brought the messa
ge to Roosevelt, he said in substance, “Mr. President, this is a very significant dispatch.” After the Chief Executive had read it carefully, he asked Beardall, “When do you think it will happen?”—referring to the outbreak of war. “Most any time,” replied the naval aide, who thought that the moment was getting very close.
Consul Nagao Kita sends the codeword HARUNA to report his codes destroyed
At the Japanese embassy at 2514 Massachusetts Avenue, the code clerks were executing these destruction orders. The code room stood at the southeast corner of the embassy, with windows overlooking the embassy parking lot and another legation next door. Half a dozen desks clustered in the middle of the room. Two cipher machines waited on desks against the west wall and a third, broken, rested in the walk-in safe. In utter disregard of the regulations promulgated for the security of communications, the embassy had hired an elderly Negro janitor named Robert to dust and clean the code room and its supersecret furnishings each day. The code clerks did make some obeisance to the security regulations by not allowing him in the room unless some Japanese were in it. But the situation was, to say the least, ironical. While the Japanese Foreign Office was exercising almost superhuman security precautions and American cryptanalysts were suffering nervous breakdowns to solve the PURPLE machine, an American citizen was running his duster over tables on which stood the intricate machines that were the vortex of this silent struggle.
But just as the Japanese seemed not to have given serious thought to the possibility of Robert’s being a spy, so the Americans seemed to have given no serious thought to the possibility that a spy might have been insinuated into the Japanese embassy to ease their cryptanalytic burden. Of course, even if they had thought about it, they might have rejected the idea, for discovery of the spy would have meant an automatic change of codes. The danger of this was much less if the systems were read through cryptanalysis.
The paper codes of the Japanese consisted of folders whose four or six pages could be opened into a single long sheet. Embassy Counselor Sadao Iguchi, who was in charge of the code room, directed telegraph officer Masana Horiuchi and code clerks Takeshi Kajiwara, Hiroshi Hori, Juichi Yoshida, Tsukao Kawabata, and Kenichiro Kondo in the burning of the paper codes. Demolition of the code machine was more complicated, and followed the guidelines transmitted recently by the Foreign Office. The machines were dismantled with a screwdriver, hammered into unrecognizability, and then dissolved in acid from the naval attaché’s office to destroy them thoroughly. Some of these operations were carried out in the gardens of the embassy; so when Bratton, who had read the code-destruction intelligence, sent an officer to the embassy to check, he obtained immediate confirmation.
Now the American officials realized the ominous meaning of the HARUNA messages that had been intercepted as they were sent from New York, New Orleans, and Havana and that had been received just that day in S.I.S. The Army and Navy high command universally regarded the destruction of codes as virtual certainty that war would break out within the next few days. As Stark’s deputy put it: “If you rupture diplomatic negotiations you do not necessarily have to burn your codes. The diplomats go home, and they can pack up their codes with their dolls and take them home. Also, when you rupture diplomatic negotiations you do not rupture consular relations. The consuls stay on. Now, in this particular set of dispatches they not only told their diplomats in Washington and London to burn their codes, but they told their consuls in Manila, in Hong Kong, Singapore, and Batavia to burn their codes and that did not mean a rupture of diplomatic relations; it meant war.”
A few hours after the code-destruction MAGIC reached Stark, he dispatched the electrifying news to Kimmel and Hart:
Highly reliable information has been received that categoric and urgent instructions were sent yesterday to Japanese diplomatic and consular posts at Hongkong X Singapore X Batavia X Manila X Washington and London to destroy most of their codes and ciphers at once and to burn all other important confidential and secret documents X
He followed this five minutes later with another message:
Circular twenty four forty four from Tokyo one December ordered London X Hongkong X Singapore and Manila to destroy PURPLE machine XX Batavia machine already sent to Tokyo XX December second Washington also directed destroy PURPLE X all but one copy of other systems X and all secret documents XX British Admiralty London today reports embassy London has complied
In Washington urgency drove out all thoughts of security. The strict injunction against ever mentioning MAGIC was completely overlooked. When Kimmel got the message, he asked Layton what “PURPLE” was. So tight had security been that neither of them knew. They checked with Lieutenant Herbert M. Coleman, the fleet security officer, who told them that it was a cipher machine similar to the Navy’s.
Marshall authorized his intelligence chief, Brigadier General Sherman Miles, to direct the military attaché in Tokyo to destroy most of his codes and ciphers:
Memorize emergency key word # 2 for use of SIGNUD without repeat without indicators destroy document Stop SIGNNQ SIGPAP and SIGNDT should be retained and used for all communications except as last resort when these documents should be destroyed and memorized SIGNUD used Stop Destroy all other War Department ciphers and codes at once and notify by code word BINAB Stop Early rupture of diplomatic relations with Japan has been indicated State Department informed you may advise ambassador
Next day after lunch the Navy followed suit in advising its Far Eastern attachés:
Destroy this system at discretion and report by word JABBERWOCK Destroy all registered publications except CSP 1085 and 6 and 1007 and 1008 and this system and report execution by sending in plain language BOOMERANG
At 8:45 p.m. that night, Thursday, December 4, the watch officer of the F.C.C.’s Radio Intelligence Division telephoned the Office of Naval Intelligence to ask if it could accept a certain message. The O.N.I. officer was not sure and said he would call back. At 9:05 GY watch officer Brotherhood called the F.C.C. and was given a Japanese weather report that sounded like something the F.C.C. man had been told to listen for. He read it to Brotherhood: “Tokyo: today—wind slightly stronger, may become cloudy tonight; tomorrow—slightly cloudy and fine weather. Kanagawa prefecture: today—north wind cloudy; from afternoon—more clouds. Chiba prefecture: today—north wind clear, may become slightly cloudy. Ocean surface: calm.” Brotherhood was relieved that it included nothing about EAST WIND RAIN, which would have meant the United States, but in any case this message seemed to lack something that would have been required in a true execute. For one thing, the phrase NORTH WIND CLOUDY, which would have meant Russia, was not repeated twice. Nevertheless, Brotherhood telephoned Rear Admiral Leigh Noyes, director of naval communications, who remarked that he thought the wind was blowing from a funny direction. The consensus was that it was not a genuine execute, and the search continued.
In Tokyo, where it was December 5, Foreign Minister Togo received representatives of the Army and Navy general staffs. A general and an admiral wanted to discuss the delicate matter of the precise timing of Japan’s final note to the United States. Drafted in English by the director of the Foreign Office’s American bureau, the note had been approved by the Liaison Conference, a six-man war cabinet, at its meeting the day before. It rejected Hull’s offer of the 26th and concluded: “The Japanese Government regrets to have to notify hereby the American Government that in view of the attitude of the American Government it cannot but consider that it is impossible to reach an agreement through further negotiations.”
Article I of the 1907 Hague Convention governing the laws of war provides that “… hostilities … must not commence without previous and explicit warning, in the form either of a reasoned declaration of war or of an ultimatum with conditional declaration of war.” Togo had suggested to the Liaison Conference that the note was far stronger than an ultimatum and that to include a specific declaration of war would be “merely to reiterate the obvious.” The conferees had gratefully a
cceded to this casuistry, since it enabled them to comply with the prior-notification requirement without endangering the surprise of the attack. Since the Hague Convention does not specify how long in advance such notification must be given, Premier Tojo and the other conferees thought to shave the time as much as possible. Dawn in Hawaii was about noon in Washington. The Liaison Conference had tentatively set 12:30 p.m., Sunday, December 7 (Washington time), as the time of delivery of the note.
But when the two military men called upon Togo the next day to fix the exact time, Vice Admiral Seiichi Ito, vice chief of the naval general staff, told the foreign minister [Togo later wrote] “that the high command had found it necessary to postpone presentation of the document thirty minutes beyond the time previously agreed upon, and that they wanted my consent thereto. I asked the reason for the delay, and Ito said that it was because he had miscalculated…. I inquired further what period of time would be allowed between notification and attack; but Ito declined to answer this, on the plea of operational secrecy. I persisted, demanding assurance that even with the hour of delivery changed from twelve-thirty to one there would remain a sufficient time thereafter before the attack occurred; this assurance Ito gave. With this—being able to learn no more—I assented to his request. In leaving, Ito said: ‘We want you not to cable the notification to the Embassy in Washington too early.’ ” In this demand lay the seeds of Japan’s juridical culpability.
Yoshikawa, in Honolulu, had continued sending his ship-disposition reports after the switch to PA-K2. They were an odd melange of accuracy, error, and outright falsehoods. On December 3, for example, he correctly reported that the liner Lurline had arrived from San Francisco but stated that a military transport had departed when no such thing had occurred. The next day he informed Tokyo about the hasty departure of a cruiser of the Honolulu class; no such ship either entered or cleared the harbor on the 4th. Then, on the 5th, he cabled that three battleships had arrived in Pearl Harbor, making a total—which he reported with deadly accuracy—of eight anchored in the harbor. His messages, sent over Kita’s signature, were decoded in the Foreign Office and routed to the North American section, where Toshikazu Kase passed them immediately to the Navy Ministry. Here they were redrafted, encoded in a naval code, and transmitted on a special frequency not normally used by the Navy and without any direct address to the Pearl Harbor strike force. Commander Koshi decoded it and brought to his chief this latest information.
