TheCodeBreakers
The next day he informed Tokyo about the hasty departure of a cruiser of
the Honolulu class; no such ship either entered or cleared the harbor on
the 4th. Then, on the 5th, he cabled that three battleships had arrived in
Pearl Harbor, making a total—which he reported with deadly accuracy—
of eight anchored in the harbor. His messages, sent over Kita's signature,
were decoded in the Foreign Office and routed to the North American
section, where Toshikazu Kase passed them immediately to the Navy
Ministry. Here they were redrafted, encoded in a naval code, and
transmitted on a special frequency not normally used by the Navy and
without any direct address to the Pearl Harbor strike force. Commander
Koshi decoded it and brought to his chief this latest information.
The communication-security precautions paid off. Whether or not the
messages slipped by the American radio monitors in Hawaii mattered
little
annaabi.ee 
