The "Winds Code" is a confused military intelligence episode relating to the Attack on Pearl Harbor, especially the advance-knowledge debate.
The Winds Code was an instruction from Tokyo to the Japanese embassy in Washington on November 19, 1941. In case of an emergency leading to the interruption of regular communication channels, a coded message would be inserted into the daily Japanese international news broadcast. Concealed within the meteorological reports, and repeated twice, would be either "East wind rain" ("Higashi no kaze ame"), "West wind clear" ("Nishi no kaze hare") or "North wind cloudy" ("Kitano kaze kumori"), the first indicating an imminent major breach with the United States, the second a break with the British (including the invasion of Thailand), the third a break with the Soviet Union.
This signal was intercepted and broken by US Intelligence (by cryptographer Commander Laurance Safford based in Washington) and, naturally, a close monitoring of the Japanese daily shortwave broadcast was instituted for the codes, dubbed the Winds Code by the Americans.
That much is clear; the problem is whether the code was ever transmitted or not. Amid all the other indicators of approaching conflict, it seems that the message was never sent, or at least never recorded at any higher level in the US command structure.
Ralph Briggs, a USN radioman, stated he logged "Higashi no kaze ame" ("East wind rain") on the morning of December 4; this was transmitted to the Fleet Intelligence Office at Pearl through the secure TWX line. Briggs was subsequently given a four-day pass as a reward (and was away in Cleveland on the 7th). At the FIO, Commander Laurance Safford states he reported this message to his superiors in Washington. At this point there is no further record of the message. Some eight other Army and Navy officers testified that they, too, had seen a winds execute message. But two of the men completely reversed their original testimony and the others turned out to have only vague recollections.
None of the official inquiries took Safford's statement as fact, the most generous reporting that he was "misled" and that his memory was faulty.
It has been claimed that in the week after the attack there was significant document 'loss' at the Office of Naval Intelligence in Washington. In 2008 historians from the National Security Agency went back and analyzed all American and foreign intelligence sources and decrypted cables. They came to the conclusion that "winds execute" message never reached Washington. If there was a message then the blame would fall on the military for not passing it on. The Japanese were very skilled in deceiving people which is why many believe that the Americans missed signs leading up to the Pearl Harbor attack.
Following the end of the war, Japanese officials advised General MacArthur that no Winds signal was ever sent relating to the United States. This is supported by the testimony of Commander Joseph Rochefort (based in Naval HQ in Pearl Harbor).
As events transpired, the Japanese had no need for a news broadcast code. Ordinary commercial communications were available to Japan right up to the December 7 attack.