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

Tensions Mount 213
On October 9 Washington cryptographers had deciphered a
September 24 “berthing plan” intercept, instructing the Japanese
consul in Hawaii to plot the location of ships in Pearl Harbor on
a grid system and to notify Tokyo. 22 However, the Pearl Harbor
commanders were not notifi ed. On December 3 Navy cryptanalysts
in Washington decoded and translated a J-19 message more
than two weeks old (November 15), sent from Tokyo to its consul
in Hawaii. It read: “As relations between Japan and the United
States are most critical, make your ‘ships in harbor report’ irregular,
but at a rate of twice a week.” 23
Again, this information was not passed on to our commanders
in Hawaii—not to General Short, who was responsible for
the safety of the fl eet while in port, and not to Admiral Kimmel,
commander-in-chief of the Pacifi c Fleet based in Pearl Harbor.
Th us the U.S. commanders in Hawaii remained ignorant of the
fact that the Japanese consul in Honolulu was keeping a close
watch on the ships of the U.S. fl eet in Pearl Harbor.
Japan Orders Its Embassy in Washington
to Destroy Codes; U.S. Naval Intelligence
Warns Outposts
On December 2, Tokyo time, the Japanese government cabled
its embassy in Washington further instructions about destroying
its codes. Th is message was promptly decoded and translated by
our Army cryptographers on December 3. 24 It said that all codes
but those now being used with the machine and all secret fi les and
documents were to be destroyed. Also, “[s]top at once using one
code machine unit and destroy it completely.” On the completion
22 Ibid., part 12, p. 261, Tokyo September 24 J-19 message to Honolulu, translated
October 9, 1941.
23 Ibid., part 12, p. 262, Tokyo J-19 message to Honolulu #111, translated
December 3, 1941.
24 Ibid., p. 215.