Japan Broke U.S. Code Before Pearl Harbor, Researcher Finds

R. A. Hettinga rahettinga at earthlink.net
Fri Dec 7 11:09:04 EST 2001


Japan Broke U.S. Code Before Pearl Harbor, Researcher Finds

Asia: Discovery is based on papers unearthed in Tokyo. They show attack may
have been prompted by belief that Washington had decided on war.
Times Staff Writer

December 7 2001

TOKYO -- Toshihiro Minohara made a startling discovery while digging
through the U.S. National Archives in College Park, Md., last summer. While
researching secret codes used prior to the attack on Pearl Harbor 60 years
ago, the young Japanese American professor stumbled upon a document,
declassified by the CIA about five years ago, that proved that Tokyo had
succeeded in breaking the U.S. and British diplomatic codes. A few
microfilmed documents, showing the Japanese translations of the telegrams,
were attached.

Minohara knew he was on to something important: For decades it was widely
believed that Japan, then a developing country with a fierce rivalry
between its army and navy, hadn't been up to measure when it came to
code-breaking, particularly the documents of the Americans.

"We are so . . . arrogant," said Donald Goldstein, a professor at the
University of Pittsburgh and co-author of "At Dawn We Slept: The Untold
Story of Pearl Harbor." "It's very possible they could have broken our
code, so why shouldn't they have?"

Research in Tokyo Confirms Findings

Further research by a colleague in Japan confirmed the findings--and may
shed light on the mind-set that caused Japan's last holdouts for peace to
opt for war just weeks before the attack, Minohara said this week.

When Minohara sent fellow Kobe University teacher Satoshi Hattori to check
Japan's diplomatic archives in Tokyo, he wasn't optimistic: Most top-secret
documents were burned after being read in wartime Japan. Those that
remained were confiscated by the U.S. during the occupation that followed
Japan's 1945 defeat; they are now housed in U.S. archives.

But Hattori unearthed a folder marked "Special Documents," containing 34
communiques that would have been easy to overlook--and apparently have been
by other Japanese researchers numerous times. They are simple typed pages,
written primarily in English, of U.S. and British diplomatic discussions
and telegrams, many from U.S. Secretary of State Cordell Hull to various
U.S. ambassadors.

The contents of the documents have long been known to historians the world
over, and some even pop up on the Internet. But their appearance in the
Japanese archives reveals that Tokyo knew what was going on in Washington
in the weeks before Dec. 7, 1941, when the Japanese attacked Pearl Harbor,
killing more than 2,000 people.

Minohara says his findings may shed light on why the few doves in the
Japanese Cabinet--in particular, Foreign Minister Shigenori Togo--dropped
their opposition to war.

Japan Stunned by Hard-Line U.S. Edict

The U.S., alarmed by the march of Japan's Imperial Army through Asia, had
imposed an oil embargo on the nation and told it to get out of China, among
other things. Togo had sent a conciliatory rebuttal, known as the "Five
Points Plan," offering some concessions and seeking to continue discussions.

Japan knew from the decoded cables that the U.S. had been seriously
considering some of the compromises. But on Nov. 26, 1941, the Americans
stunned Japan with a hard-line edict essentially ordering Tokyo's troops to
get out of China and Indochina or face the consequences. This apparently
convinced even Togo that the U.S. had decided on war.

Many historians have speculated that President Franklin D. Roosevelt was
looking for an excuse to get into the war in Europe; they posit that he
knew Japan would attack but thought the target might be American forces in
the Philippines or instead perhaps Malaya, then a British colony, which
would prompt the U.S. to come to the aid of its ally.

The newly revealed documents raise an interesting question, Minohara says.
Had the American side accepted the compromises it was considering--lifting
the oil embargo for three months, permitting Japanese troops to remain in
Indochina and continuing discussions on Japan's occupation of
Manchuria--would Tokyo have still gone through with the surprise attack on
Pearl Harbor?

Japan's war vessels had long before set sail for the Pacific, and the
command "Climb Mt. Itaka" meant for Japanese troops to go forward with the
attack on Pearl Harbor; but there was also a lesser-known command, "Climb
Mt. Tsukuba," which meant return.

"The big question is why the U.S. dropped the offer," says Minohara, 30,
who did undergraduate work at UC Davis before moving to Japan for graduate
school at Kobe University, where he now teaches.

Togo wrote in his memoirs that, when he read the edict from the U.S., "I
was shocked to the point of dizziness. At this point, we had no choice but
to take action."

Historians often wondered why he was so shocked. Minohara says Togo's
raised expectations that a deal was in the offing led to his anger.

Thomas G. Mahnken, a strategy professor at the U.S. Naval War College in
Rhode Island who recently completed a book on U.S. intelligence on Japan in
the years before World War II, says the knowledge that Japan was breaking
the codes is "significant."

Then again, Mahnken notes, the U.S. diplomatic telegrams "were not
tremendously sophisticated," and a number of countries had even broken
those used by military attaches.

Neither Japan nor the U.S. had broken the other's military codes prior to
Pearl Harbor, Minohara says.

Japanese historians often claim that the U.S. misinterpreted some of the
country's telegrams--for instance, that Togo's "Five Points Plan" was
translated as a "final offer" when Togo never said that.

Minohara says the Japanese "were doing the same thing. Even though there
was no error in the translations, they were still misinterpreting the U.S.'

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R. A. Hettinga <mailto: rah at ibuc.com>
The Internet Bearer Underwriting Corporation <http://www.ibuc.com/>
44 Farquhar Street, Boston, MA 02131 USA
"... however it may deserve respect for its usefulness and antiquity,
[predicting the end of the world] has not been found agreeable to
experience." -- Edward Gibbon, 'Decline and Fall of the Roman Empire'

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