Marshall had Tom Dewey keep a US code secret

Gen. George Marshall asked Thomas Dewey during the 1944 presidential campaign not to reveal that the United States had broken Japanese diplomatic codes -- and might have known of the plans to attack Pearl Harbor, the Washington Post reported Monday.

Citing documents just declassified by the National Security Agency, the Post said General Marshall -- Army chief of staff -- secretly made that request to Mr. Dewey, the Republican nominee campaigning to oust President Roosevelt, because the Japanese were still using the same codes at the height of the Pacific war.

The Post said Dewey, then governor of New York, never revealed the secret, but he remained convinced that Mr. Roosevelt had prior knowledge of the Pearl Harbor attack.