 On 10 June , the Imperial Japanese Navy conveyed to the military liaison conference an incomplete picture of the results of the battle . Chūichi Nagumo 's detailed battle report was submitted to the high command on 15 June . It was intended only for the highest echelons in the Japanese Navy and government , and was guarded closely throughout the war . In it , one of the more striking revelations is the comment on the Mobile Force Commander 's ( Nagumo 's ) estimates : " The enemy is not aware of our plans ( we were not discovered until early in the morning of the 5th at the earliest ) . " In reality , the whole operation had been compromised from the beginning due to Allied code @-@ breaking efforts . 
