Japanese code reading and consular intelligence

Could Japan read American codes before Pearl Harbor?

Japan could read some American codes and also benefited from a capable intelligence service and consular reporting from Hawaii.

Japan could read at least some American codes and maintained an effective intelligence-gathering service. The claim is limited to some American systems rather than a complete compromise. Japanese planners therefore did not assess Pearl Harbor entirely blind. The Japanese consulate also supplied current information about the fleet's condition, giving the strike planners another intelligence channel.