He was part of a team instrumental in breaking Japanese naval codes.

They had been working on Japanese diplomatic codes.

And more significantly, the Japanese diplomatic code had been broken by American intelligence.

A more direct influence on the social system itself was the new Japanese civil code of 1898.

United States intelligence broke the Japanese code early in the war.

For more than a year, American cryptanalysts had been breaking a key Japanese code.

He was also employed as a code-breaker, managing to break an important Japanese code.

Not long after that, other technologies helped crack the Japanese military code.

American intelligence could read the Japanese diplomatic (but not naval) codes and knew that war was a very strong possibility.

Roosevelt, for instance, failed to give priority to breaking Japanese naval codes in 1940-41.