4.7. What the Japanese Said about the Winds Execute Message
Based on the FCC and naval intercept, it is clear that the Japanese broadcast the Winds Execute message, specifically "West Wind Clear," on 7 December (8 December Tokyo time) 1941. Japanese sources, though, contradict one another as to what time that day they actually broadcast the phrase and what coded phrases were sent out over the airwaves. However, it is certain from the evidence that the message was sent only on that day and possibly into the next, considering the time zone difference.
After the war, military investigators for the Advance Headquarters, U.S. Army Forces Pacific, Tokyo, searched the extant records of the Japanese Broadcast Corporation and interviewed its employees regarding the transmission of any Winds messages. The American investigators discovered that most of the records of the corporation, like the records from most of the departments of the Japanese government and the branches of its armed forces, had been destroyed in the two weeks between Tokyo's acceptance of surrender terms and the arrival of the American occupation forces.[] So the investigators concentrated on interviewing the corporation's employees about the coded Winds messages. They did this without revealing the source of their information – the Winds instructions derived from the decrypted messages Nos. 2353 and 2354 of 19 November 1941.
Initially, the Japanese radio station workers denied knowing anything about the Winds messages. Contrary to some assertions, these denials should come as no surprise. Many Japanese civilian government employees had heard rumors that Americans would execute "war criminals" and were afraid of revealing their participation, no matter how minor or tangential, in any prewar government activities. This fear was common among many Japanese intelligence officials and cryptologists.[] But when confronted with copies of the 19 November tasking messages, again, without being told their source, the Japanese admitted that such a code phrase was sent, but not until 8 December and that the message was most likely sent on an overseas broadcast sometime after 2:30 AM, 8 December 1941, Tokyo time (7:00 AM, Honolulu and 12:30 PM, Washington).[]
One employee, who was stationed in Rangoon, Burma, during late 1941, told investigators that he had heard the signal on the voice broadcast on 8 December at 6:30 AM (9:30 AM Tokyo time and 2:00 PM, 7 December, Honolulu). Upon further questioning, he stated that he had heard only one coded phrase, which he could not specifically recall, but he believed it to have applied only to Japan's relations with Great Britain.[] The broadcast time that he remembered was a little over six hours after the attack on Pearl Harbor. This recollection coincided with the time the FCC monitors heard the two stations broadcast "West Wind Clear" between 12:00 and 1:00 AM, 8 December, GMT (7:00 PM, Washington; 1:30 PM, Honolulu).
During this same period, representatives from the U.S. Navy Technical Mission to Japan interviewed Shinroku Tanomogi, the chief of the Overseas Department of the Japanese Broadcast Corporation. [Exhibit 35][] He told his American questioners that at 4:00 AM on 8 December (8:30 AM, 7 December, Honolulu) he had received a call from the Information Bureau of the cabinet that Japan was at war and therefore scheduled programs would have to be rearranged to handle government communiqués.
When the Americans asked Tanomogi about a Winds weather broadcast being sent at 1500 hours (3:00 PM), he said he had a "vague recollection" that there had been one among the reports being readied for the news program. However, he added that he had not listened to any of the ensuing programs. The Navy report did not specify in what time zone the 3:00 PM reference occurred. If the investigator meant Tokyo time, then the broadcast would have been made six hours after the one heard by the FCC, or sometime around 1:00 AM, 8 December in Washington. If they meant Honolulu time, then the broadcast would have been within an hour of when the FCC station in Hawaii heard "West Wind Clear." But the time zone was not further identified. Tanomogi could not recall for his interlocutors if he had heard any coded Winds message.
In 1960, in an article in the United States Navy Institute Proceedings, Takeo Yoshikawa, the Japanese intelligence agent in Honolulu who had sent all of the reports about the Pacific Fleet and air defenses in Pearl Harbor prior to the attack, stated he had heard the Japanese National Broadcast give a special weather report on its program at 0800 (8:00 AM, Honolulu and 3:30 AM, 8 December, Tokyo) 7 December 1941. Yoshikawa said that he had heard the coded phrase "East Wind Rain," which was sent twice in the broadcast. He added, "That this meant that the imperial council in Tokyo had decided for war with the United States."[]
Another employee of the Japanese Broadcast Corporation, Morio Tateno, though, disputed this version of events. Tateno claimed in an interview that he had read that same news broadcast with the inserted Winds coded phrase that Yoshikawa had heard, except that the phrase he read was not "East Wind Rain," but "West Wind Clear," the warning of a change in relations with Great Britain. [Exhibit #46][]
Tateno asserted that he had been told at 2:00 AM (Tokyo time) to be ready to read a broadcast with a special weather report. However, he was not given the forecast until the 3:00 AM program. He said he read the phrase "West Wind Clear" twice during the 3:00 AM and 4:00 AM newscasts Tateno did not give the call letters of the station that broadcast the program, nor does he mention if any other broadcasts were made at his station or any others during the rest of the day. This lack of information about the broadcast station is important since the broadcast time and frequency would have determined what regions would have heard the transmission of the coded Winds message. While such a broadcast might have been intended for North America, it is just as likely it would have been beamed to Japanese facilities in Southeast Asia.
If Tateno's version of events were correct, then the news programs would have been heard in Honolulu at both 7:30 and 8:30 AM on 7 December. For Yoshikawa to have heard the program at 8:00 AM in Honolulu, it means the broadcast would have been made at 3:30 AM, 8 December in Tokyo. Tateno's version also conflicts with the reports of the Federal Communications Commission whose monitors in Hawaii and Oregon heard the Winds code phrase several hours after the attack, as well as the Navy officers manning the intercept site in Hawaii who heard it hours after the strike.[] Tateno's version also conflicts with Tanomogi's narrative, which has the special communiqués arriving at the station about 4:00 AM (Tokyo time).
Even conceding that the Japanese might have sent a Winds Execute thirty minutes before the attack does not mean a warning could have been sent out by U.S. intelligence. Recall that there was no direct link from the coded Winds messages to any particular Japanese action or deadline. So the warning value was nil. But even if such a transmission had been heard, if we recall that it took hours before the news of the "mistaken" Winds message of the evening of 4 December reached the OP-20-GY watch center, then any intercept of 7 December would have taken hours to process, and then any warning would have arrived hours after the attack.
Still, regarding the evidence from Japanese sources, while some information was contradictory about the precise timing of the broadcast of the Winds code phrase, they all agree that none occurred before 7 December.