3.1. The Search Begins – 28 November 1941
By 28 November, with the two translations of the Japanese Gaimusho messages setting up the Winds code phrases and words, along with the message from the Commander-in-Chief Asiatic Fleet, Admiral Thomas Hart, which reported the British exploitation of the same two messages, American naval intelligence was ready to act. The Director of Naval Intelligence (ONI), Rear Admiral Theodore Wilkinson, passed a request through the Director of Naval Communications (DNC), Rear Admiral Leigh Noyes, that the communications intelligence arm of DNC was to make every attempt to intercept any Winds Execute message. Noyes seconded the request to Captain Safford, adding that it was to be construed as an order.[]
The first thing the American cryptologists had to do before any tasking could be set for monitoring for the Winds Execute messages was to draw up a list of Japanese commercial radio stations that might transmit the phrases or words, along with their operating frequencies and broadcast schedules. Fortunately, in the preceding months, the Americans had translated a number of Japanese diplomatic messages that dealt with the ability of Tokyo's embassies and consulates around the world to hear these broadcasts stations. The diplomats had reported back to Tokyo both on the strength of the transmissions and their clarity. In many cases, the diplomats reported any problems with regional atmospherics or interference from local transmitters. These reports included the voice programs on the high frequency band (3 to 30 MHz), as well as those voice and Morse code transmissions on the medium frequency band (300 kHz to 3 MHz) and even lower.[] The Americans, then, already had a good sense of the capabilities of Japanese overseas broadcasts.
On 27 November Tokyo sent a message to the Washington embassy that included a set of broadcast schedules and frequencies for four Japanese news broadcast stations to various parts of East Asia, the Pacific coast of the United States, and Europe.[] The contents of the message were available to the Americans the next day:
Captain Safford took the schedule from this message and made it the main part of a technical message that the CNO staff (OPNAV) sent out to a number of navy commands the very next day. In sending out this message, he had acted quickly, he said later, because "it would be a feather in our cap if the navy got it [the Winds Execute message] and our sister service did not."[] The message was sent at priority precedence to naval intercept and analytic elements in the Philippines and Hawaii. But it seems that Safford may have acted a bit precipitously in sending out this information. Some of the data in the OPNAV message was incomplete, incorrect, and not current. Safford also had failed to take into consideration what broadcasts the various navy field sites could hear due to propagation and local reception conditions.
More importantly, the OPNAV message as sent had not tasked any navy site to listen for the Winds code phrases or words. The sole correspondence that had mentioned any monitoring activity was the 28 November message from Admiral Hart's Asian Fleet command notifying Hawaii and Washington that his command and the British at Singapore would be listening for the Winds code words or phrases. But this message from the Far East was not followed up by one from OP-20-G, ONI, or the DNC that detailed any further tasking for navy intercept sites. Instead, the OPNAV message contained only the technical information on Japanese broadcast schedules that Safford had compiled from the translation of the Japanese message with the schedules.
In the technical message to Hawaii and the Philippines, Safford departed a bit from the information in the Japanese listing. For one thing, he assumed that all the broadcast times were in Tokyo time. Secondly, he presumed that the broadcast schedule times for station "JVJ" at 6:00 and 7:00 PM were for the Pacific coast. While possibly valid, these assumptions were not necessarily correct, either. Recall that the broadcast schedule had been sent only to the embassy in Washington. The question implicit in the message from Tokyo was whether or not these broadcasts could be heard by the embassy.
On 27 November the Japanese embassy in Washington had responded to the broadcast schedule message. In it, the embassy noted that it could only poorly receive the broadcasts from stations JUO and JVJ and that Tokyo had to replace those stations with broadcasts from stations JAV (27.327 MHz) and JUP (13605 KHz). Also, Washington wanted the frequency for JHL changed to 13605 KHz from 5160 KHz. Yet Safford did not mention these modifications in his 28 November message. Nor did he note in the OPNAV message that stations JUO and JVJ, as well as their replacements, JAV and JUP broadcast in Morse code, while JHL was a voice program, the Domei news broadcast.[] The importance of this distinction was that for a monitoring site to copy a voice broadcast required the presence of individuals qualified in the Japanese language.
These differences took on importance when, on 28 November, OP-20-GX, the element in OP-20-G that was responsible for tasking the navy's monitoring stations, sent the same text of Safford's message via TWX (teleprinter exchange via leased cable lines) to Stations "M" at Cheltenham, Maryland, and "S" at Bainbridge, Washington. Again, as in the earlier message, no mention was made of any Winds code phrases. When the message was received at the station, the personnel there requested a clarification of the times of the broadcasts – specifically were these Greenwich Civil Time (GCT) or Pacific Standard Time (PST)? OP-20-GX told Bainbridge that the time zones were uncertain and unverifiable. On their own initiative, the personnel at Bainbridge recalculated the frequencies and times of the stations they could hear. The resulting schedule, though, was quite different from the list from Washington.[] At Bainbridge there were no Japanese linguists qualified to monitor voice transmissions, so it could only record the broadcasts made by voice.[]
In the Philippines at the navy's communication intercept station on Corregidor Island in Manila Bay, known as "C" or "Cast," coverage of the broadcasts was assigned to two receivers, one for the voice and one for the manual Morse broadcast. A Japanese-qualified linguist was assigned to monitor the voice transmissions, while all intercept copied from both receivers was reviewed by another linguist for any sign of the Winds code phrases or words.[]
In Hawaii, the chief of naval intelligence for the Fourteenth Naval District, Captain I.H. Mayfield, acting possibly in conjunction with instructions from Admiral Kimmel's command, ordered two language-qualified officers to monitor Japanese language programs broadcast by the local commercial radio stations KGU and KGMB. Both officers were instructed what phrases and words to listen for during their monitoring. Both were further told that if any such phrases were heard, then they were to report the information to Mayfield, Commander Edward Layton, Pacific Fleet Intelligence Officer, or Commander Joseph Rochefort, the commander of the Communications Intelligence Unit (CIU) subordinate to the 14th Naval District, otherwise known as Station HYPO or "H." Oddly, since there was no information about broadcasts of the Winds Execute phrases or words appearing on local U.S. stations, precisely why the District Intelligence Officer ordered this monitoring is unclear.[] It is possible that Mayfield misunderstood the instructions and believed that the phrases or words would appear on the local Japanese language programs. It is also possible that the navy believed that instructions to the local Japanese population to commit sabotage might be passed on these same programs in the same code.[]
Also in Hawaii, four Japanese language-qualified naval officers were transferred from the Rochefort's code-breaking center in Pearl Harbor and stationed in Heeia on the northern side of Oahu. They were ordered to maintain a twenty-four-hour watch on overseas Japanese language broadcasts. These four officers were briefed on the three phrases to listen for and their meaning. They were further told to inform Commander Rochefort if they heard such phrases.[] The officers listened to the Japanese news broadcasts and paid particular attention to the programs on the hour and half-hour when weather forecasts were more likely to be sent.[]
On 28 November the SIS head of intercept operations, Captain Robert Schukraft, after consulting with Colonel Otis Sadtler, contacted, via teletype, the Army's Monitoring Station No. 2 at the Presidio in San Francisco and instructed them to listen to the Japanese general intelligence broadcast. He also drove to Monitoring Station No. 7 at Fort Hunt, Virginia, and personally delivered intercept instructions.[] Some five days later, the Army's SIS tasked several of its monitoring stations located in the Philippines, the Panama Canal Zone, the Presidio in San Francisco, Fort Sam Houston, and the Signal School at Fort Monmouth, New Jersey, to "copy all Japanese plain text in addition to code text diplomatic traffic. Stop. This traffic will be forwarded with regular traffic."[] The army's message is peculiar in two ways. First, it was sent out some five days after the translations of the Winds instruction messages were available. Secondly, the tasking message never mentions the Winds Execute phrases or words, simply to copy all Japanese plaintext, which could result in the collection of a high volume of traffic with no sense of exactly what was being sought by SIS headquarters.
Late on the afternoon of 28 November, a Colonel Wesley Guest from the staff of the Army's Chief Signal Officer called the chief of the Radio Intelligence Division (RID) of the Federal Communications Commission, George Sterling, and asked that the Commission alert its numerous radio monitoring stations to listen for the Winds Execute phrases. The FCC was an independent agency in the federal government charged with management of the radio spectrum in the United States, as well as the enforcement of regulations for radio licensing and operations. As part of its charter, the FCC also listened for illegal or illicit communications. It also monitored foreign broadcasts and delivered full transcripts or summaries to departments of the government such as the Department of State. Sterling, a field engineer with experience in radio communications going back to the First World War, had organized a special division of the FCC, the Radio Intelligence Division, to copy military, naval, and illicit (agent) communications, using the FCC's almost four dozen monitoring stations located throughout the continental United States and overseas territories like Hawaii. The FCC also had worked with the FBI in targeting Axis communications from Latin America beginning in 1940.
The Army's instructions, though, limited the FCC to listening for the three phrases that were to be sent over the Japanese voice broadcasts. Guest further asked that if any of the three phrases were heard the FCC watch center should notify Colonel Rufus Bratton, the chief of the Army's Far East Intelligence Section of G-2. Bratton gave the FCC watch office his work and home phone numbers and told them to contact him anytime they heard the phrases. The Army failed to pass along to the FCC important technical information such as broadcast schedules, call letters of the suspected Japanese broadcast stations, or their operating frequencies. While Sterling accepted the Army's request, he disagreed with the Army's projection (based on the Navy's data) that the Japanese broadcast might be heard by the FCC's monitoring stations on the U.S. east coast like the one at Laurel, Maryland. Instead, he assigned primary coverage to the FCC station in Portland, Oregon.[]
Figure 3.1. George Sterling, Chief, Radio Intelligence Division, FCC
If the servicemen and the FCC monitors were to have any chance to hear the critical words or phrases, they were going to have to listen to a number of Japanese broadcasts, both in the Morse code and voice. Navy analysts and radio intercept operators were given index cards with the relevant phrases in Kana, the Japanese phonetic syllabary script adapted for Morse code, as a means of quick reference to check intercept. Some officers carried the cards around while on duty and a few even took them home for reference in case they were called by phone with a possible intercept. Hawaii and Station "Cast" in Corregidor screened Japanese broadcasts for the next several days until the war started, dutifully copying down Kana news broadcasts and turning them over to a linguist to review.
A major drawback to this close coverage of Japanese radio broadcasts was that it forced major changes to current target lists and operations of the affected field sites. All of the tasked army and navy monitoring sites already had significant numbers of Japanese communications links as their primary and secondary targets. Now, these field sites had to amend standing intercept target lists to accommodate coverage of these broadcasts. These sites had a limited number of receivers and intercept operators to cover the new intercept targets. While the highest priority, usually high-level diplomatic or naval communications links, would not be affected, site coverage of Japanese and other nations' communications stations considered nonpriority would be displaced. On 4 December the Director of Naval Communications, Admiral Leigh Noyes, in whose organization the OP-20-G resided, complained to Admiral Wilkinson at ONI about the assigned broadcast coverage. He pointed out to Wilkinson that the Federal Communications Commission had over 450 radio receivers to monitor overseas broadcast. He suggested that in Hawaii, for example, the Navy could not duplicate the work of the local FCC component.[] In 1941 the Navy had barely a third of the receivers that the FCC had for its global coverage. Of these, about sixty in the Pacific were available for the Winds coverage, that is, at the stations at Bainbridge, Hawaii, and the Philippines, but most of these already were tasked with priority monitoring of Japanese naval, merchant ship, and diplomatic radio terminals.[]
The British attached much the same importance to the possible Winds Execute message as had the Americans and accordingly set up means to intercept it. The British in Singapore had intercepted the two "setup" messages, as had their partners the Americans and Dutch. The FECB had shared this information with their station in Hong Kong and the Americans at Corregidor. The Bureau in Singapore instructed the listening post in Hong Kong on Stonecutters Island to monitor Japanese commercial broadcasts for the Execute message. At the S.I. section in Singapore a special receiving set was installed and a watch schedule of Japanese language officers was started. This special arrangement was necessary because the nearby intercept site at Kranji was staffed entirely by Morse intercept operators who were not able to listen to Japanese language broadcasts – a predicament similar to that at American listening stations, where, as in the case at Hawaii, a number of linguists had to be detailed to review the intercept of the broadcasts every day.[]
Meanwhile, Army and Navy analysts and linguists were literally buried under the new intercept they had to review. One estimate was that the weekly normal intercept received at OP-20-G by teletype increased from about three to four feet of copy per week to as much as 200 feet per day![] Then Lieutenant Alwin Kramer, an ONI Japanese language-qualified officer on loan to OP-20-G, recalled later that there were only three linguists available to translate all of the copy and that the volume of it was "simply tremendous, swamping."[] The Army's analytic personnel were similarly beleaguered with the demands of the new priority coverage.[]
Considering the varying degrees of expertise in the Japanese language and broadcasts, as well as the partial or vague tasking to the Navy, Army, and FCC sites, it should have come as no surprise that there were instances of mistaken intercept, false alarms, and confusion of the Winds Execute message with regular Japanese weather reports. In the week preceding Pearl Harbor, a number of such mistakes or false alarms occurred.
The first incident occurred on 1 December. The navy intercept station at Corregidor informed both Hawaii and Washington that a Japanese broadcast station, JVJ, one of the stations listed on the technical message from OP-20-G on 28 November, had stated on its afternoon program that "all listeners be sure and listen in at 0700 tomorrow morning since there may be some important news." According to the Pacific Fleet Intelligence officer in Hawaii, Commander Edwin Layton, the "impression" at that time was that the Winds Execute message would be broadcast then. The officers monitoring the voice broadcasts and the Morse news programs were ordered to listen for the important news, but no such message or notice was heard on JVJ or any other station.[]
Meanwhile, the FCC monitoring site in Portland, Oregon, which had begun its monitoring on 28 November, started to pick up a number of broadcasts that contained weather phrases that appeared to resemble the Execute message. As instructed, the FCC watch officer dutifully called Colonel Bratton with what was believed to be Winds Execute phrases. On 1 December he called Bratton at 5:45 PM (EST) and on 3 December again called him, probably at home, at 7:35 PM (EST). The watch officer also called George Sterling to apprise him of the intercepted broadcasts. But as Colonel Bratton would recall later, these FCC intercepts were mistaken or false alarms. Bratton also said he notified naval intelligence officials, in this case Captain McCollum and Lt. Alwin Kramer, of the FCC intercept reports.[]
One of the more significant erroneous intercepts occurred at 1700 hours EST (5:00 PM) on 4 December when the FCC monitoring station in Portland, Oregon, overheard a weather broadcast by Tokyo station JVW3 (not on the OPNAV or the Japanese lists by the way) that appeared, at first, to fit the Winds format. [Exhibit #22, page 2[] and Exhibit 23, page 1[]] The phrase "North Wind Cloudy" was heard, which indicated a break in relations with the Soviet Union. Within three hours of Portland, reporting the phrase, the FCC watch officer in Washington, unable to contact Colonel Bratton or his assistant, reported the intercept to the OP-20-GY watch officer, Lt. Francis M. Brotherhood, USN, at about 8:45 PM (EST). After checking with his superiors, Brotherhood called the FCC back at 9:00 PM and wrote down what the FCC site had intercepted. Lt. Brotherhood recalled that the message seemed to be "missing" something from what he had been led to expect. He probably checked his instructions and realized that there was no mention of the phrase relating to relations with America, HIGASHI NO KAZEAME.
Brotherhood then called Admiral Noyes at his office on a special (probably secure) telephone. Brotherhood repeated to Noyes the phrase from the broadcast the FCC had heard. Brotherhood recalled that Noyes had said something to the effect that the "wind was blowing from the wrong direction."[] More to the point, the FCC had heard the "North Wind Cloudy" phrase only once in the broadcast, instead of the required two times in the middle and end of the news program. Also, the same broadcast carried the phrase "North Wind Slightly Stronger May become Cloudy,' as well as the phrase "North Wind Clear." It was obvious this was not the Winds Execute message. At 9:30 PM, Brotherhood did call back to the FCC to check if any there were any other references to the weather in the program, but was told there were none. [Exhibit #24, page 4][]
This report of an erroneous winds report echoed into the following Friday morning, 5 December. At about 9:00 AM, Colonel Bratton was called to a meeting in the office of the Army's G-2, Major General Sherman Miles. Lieutenant Colonel Otis Sadtler, a Signal Corps officer attached to G-2, told Bratton that Admiral Noyes, the Director of Naval Communications (OP-20), had called him and said that the "weather" message was in. Bratton referred to his card with the code phrases and words and asked Sadtler what the message said and whether it was in either English or Japanese. Sadtler was not certain and said that the report might be a false alarm. Interestingly, he said that Noyes had indicated that the message referred to Great Britain and Japan.[]
Figure 3.2. Lieutenant Colonel Otis K. Sadtler
According to Bratton, he told Sadtler to call Noyes, confirm the intercept and to get a copy of it for the army. Sadtler contacted Noyes over a secure telephone between G-2 and the DNC. Noyes, Sadtler reported to Bratton, told him again that it was the phrase that referred to relations between Great Britain and Japan, but that he did not have the Japanese text. Bratton still wanted confirmation and told Sadtler to get the text. Bratton never saw Sadtler again that day. Meanwhile, Bratton called naval intelligence and spoke either to Captain McCollum or Lt. Kramer who told him that they had not received any Winds message. Bratton also called the SIS office and was told that no Winds message had come in.
The SIS had seen a copy of this mistaken Winds message. Colonel Sadtler had obtained a copy of the FCC teletype and showed it to Captain Robert Schukraft. He saw about two lines of text and immediately realized it was not the correct format and therefore not the expected execute message.[] Unfortunately, word of the intercept, though not verified, continued to be spread around the navy and army offices. Sadtler had told Major General Leonard Gerow, chief of the War Department's Planning Division, and Colonel Walter Smith, assistant of General George Marshall, that the "Winds was in." Later in the day, Noyes informed Admiral Richard Turner, chief of the Navy's War Plans Division (OP-12), that a weather message was in, but that it referred to the Russians and that it seemed "wrong."[]
Another mistaken Winds Execute message was heard on the evening of 5 December. The same station, JVW3, at 9:30 PM (Tokyo time) broadcast a weather report that read "TODAY NORTH WIND MORNING CLOUDY AFTERNOON CLEAR BEGIN CLOUDY EVENING. TOMORROW NORTH WIND AND LATER FROM SOUTH." [Exhibit #22, page 167[] and Exhibit 23, page 172[]] This report was repeated three times. A half hour later, the FCC monitors in Portland heard the same station send a timing signal. and then an announcer came on the air and said, "I will now give the weather report," but then halted.
The Portland monitoring site watch officer called George Sterling with a report of this transmission. Sterling then called Colonel Bratton and read him the text. Bratton realized that the format of the transmission was not as specified in the original Japanese instructions. The phrase did not appear in the middle or end of the news program. Also the phrase was not exact – "North Wind Morning Cloudy" – and was stated only the one time.[] Still, Bratton told Sterling, "he was encouraged by the reporting," and that "we have that much more time." [Exhibit 24, pages 177 and 181][] This last comment suggests that Bratton believed that with the continued absence of the Winds Execute phrases and words that an anticipated Japanese deadline in United States-Japan relations had not yet been reached. Interestingly, when Sterling asked Bratton if he should inform the Portland site that the weather phrases would appear in the middle and end of a news program, Bratton said that he would get back to Sterling on that issue.[]
While the Americans struggled with processing the increased broadcast intercept and encountered a number of "false alarms," the Japanese already had begun to add new instructions for their diplomats about the destruction of classified material.