Pearl Harbor: The Seeds and Fruits of Infamy - Ludwig von Mises ...

U.S. Military Plans and Preparations 89
regular basis. Given that fact, plus Stark’s reassurance that ONI
would keep him informed, Kimmel assumed he was being sent,
and would be sent, all the information of value that Washington
could supply.
Security Leak in Washington
Since August 1940 we had been intercepting and decoding
messages sent in the Japanese diplomatic cipher, designated
“Purple.” Th is enabled us to read messages to and from Japan’s
embassies all around the world. Th ese secret intercepts came to
be called MAGIC and were surrounded by strict security. Except
for the cryptographers and translators, they were seen by only a
handful of top people in the administration and the services. Th en
in the spring of 1941 it was discovered that one copy of a decoded
Japanese intercept was missing from the fi les. A “magic translation
. . . was lost in the State Department. Th e Army had sent it to
them and it never came back.” 26 In the words of Commander L.F.
Saff ord, then in charge of communications security, “all hell broke
loose.” A missing message was a serious matter. If the Japanese
learned we could read messages sent in their complex diplomatic
code, which we had deciphered at a cost of much time and eff ort,
they would probably change it. We would then be deprived of an
extremely valuable source of intelligence.
Saff ord and the others concerned with security could not
imagine where this missing message had gone. However, in April
and May we intercepted several “Purple” messages between Berlin
and Tokyo indicating that German intelligence sources, probably
in the United States, believed that the U.S. government had deciphered
some Japanese codes. Tokyo cabled Berlin on April 16,
“We suspect that the several codes I b , 80 c and OITE d are being
26 Ibid., part 8, p. 3735.