Report Debunks Theory That the U.S. Heard a Coded Warning About Pearl Harbor

It has remained one of World War II’s most enduring mysteries, one that resonated decades later after Sept. 11: Who in Washington knew what and when before the Japanese attacked Pearl Harbor on Dec. 7, 1941?

Specifically, who heard or saw a transcript of a Tokyo shortwave radio news broadcast that was interrupted by a prearranged coded weather report? The weather bulletin signaled Japanese diplomats around the world to destroy confidential documents and codes because war with the United States, the Soviet Union or Britain was beginning.

In testimony for government inquiries, witnesses said that the “winds execute” message was intercepted as early as Dec. 4, three days before the attack.

But after analyzing American and foreign intelligence sources and decrypted cables, historians for the National Security Agency concluded in a documentary history released last week that whatever other warnings reached Washington about the attack, the “winds execute” message was not one of them.

A Japanese message intercepted and decoded on Nov. 19, 1941, at an American monitoring station on Bainbridge Island, in Washington State, appeared to lay out the “winds execute” situation. If diplomatic relations were “in danger” with one of three countries, a coded phrase would be repeated as a special weather bulletin twice in the middle and twice at the end of the daily Japanese-language news broadcast.

“East wind rain” would mean the United States; “north wind cloudy,” the Soviet Union; and “west wind clear,” Britain.

In the history, “West Wind Clear,” published by the agency’s Center for Cryptologic History, the authors, Robert J. Hanyok and the late David Mowry, attribute accounts of the message being broadcast to the flawed or fabricated memory of some witnesses, perhaps to deflect culpability from other officials for the United States’ insufficient readiness for war.

A Congressional committee grappled with competing accounts of the “winds execute” message in 1946, by which time the question of whether it had been broadcast had blown into a controversy. The New York Times described it as a “bitter microcosm” of the investigation into American preparedness.

“If there was such a message,” The Times wrote, “the Washington military establishment would have been gravely at fault in not having passed it along” to military commanders in Hawaii. If there was not, then the supporters of those commanders “would have lost an important prop to their case.”

In an interview, Mr. Hanyok said there were several lessons from the controversy that reverberate today. He said that some adherents of the theory that the message was sent and seen were motivated by an unshakable faith in the efficacy of radio intelligence, and that when a copy of the message could not be found they blamed a cover-up — a reminder that no intelligence-gathering is completely foolproof.

Washington also missed potential warning signs because intelligence resources had been diverted to the Atlantic theater, he said, and the Japanese deftly practiced deception to mislead Americans about the whereabouts of Tokyo’s naval strike force.

“The problem with the conspiracy theory,” Mr. Hanyok said, “is that it diverted attention from the real substantive problems, the major issue being the intelligence system was so bureaucratized.”

Beginning about Dec. 1, Washington became aware that the Japanese were ordering diplomats overseas to selectively destroy confidential documents. But, the N.S.A. study found, “because of the sometimes tardy exploitation of these messages, intelligence officers in the Army and Navy knew only parts of the complete program.”

“It is possible,” the study went on, “that they viewed the Japanese actions as ominous, but also contradictory and perhaps even confusing. More importantly, though, the binge of code destruction was occurring without the transmittal of the winds execute message.”

The authors concluded that the weight of the evidence “indicates that one coded phrase, ‘west wind clear,’ was broadcast according to previous instructions some six or seven hours after the attack on Pearl Harbor.”

“In the end, the winds code never was the intelligence indicator or warning that it first appeared to the Americans, as well as to the British and Dutch,” they wrote. “In the political realm, it added nothing to then current view in Washington (and London) that relations with Tokyo had deteriorated to a dangerous point. From a military standpoint, the winds coded message contained no actionable intelligence either about the Japanese operations in Southeast Asia and absolutely nothing about Pearl Harbor.

“In reality,” they concluded, “the Japanese broadcast the coded phrase(s) long after hostilities began — useless, in fact, to all who might have heard it.”

That war with Japan was anticipated is apparent from a separate memorandum to President Franklin D. Roosevelt dated Nov. 13, 1941, from William J. Donovan, director of the Office of Strategic Services, the precursor to the Central Intelligence Agency. The memorandum was found in the National Archives last year by the Nazi War Crimes and Japanese Imperial Government Records Interagency Working Group.

Reporting on a conversation the week before between Hans Thoman, the German chargé d’affaires to the United States, and Malcolm R. Lovell, a Quaker leader, Mr. Donovan quoted Mr. Thoman as saying that Japan was trying to buy time.

“In the last analysis, Japan knows that unless the United States agrees to some reasonable terms in the Far East, Japan must face the threat of strangulation, now or later. Should Japan wait until later to prevent this strangulation by the United States, she will be less able to free herself than now, for Germany is now occupying the major attention of both the British empire and the United States.

“If Japan waits, it will be comparatively easy for the United States to strangle Japan,” Mr. Donovan’s memorandum quoting Mr. Thoman continued. “Japan is therefore forced to strike now, whether she wishes to or not.”

This article has been revised to reflect the following correction:

Correction: December 14, 2008
An article last Sunday about a new report debunking a theory that the United States heard a coded warning about the Pearl Harbor attacks misspelled the surname of the German chargé d’affaires to the United States at the time, who was quoted in a government memorandum from November 1941 predicting that war between the United States and Japan was inevitable. He was Hans Thomsen, not Thoman.

Source : The New-York Times, December 6, 2008.