By analyzing all the available Secret Message Serial (SMS) numbers originated by the Japanese CinC 1st Air Fleet, it is clear that no messages were sent by radio during the formation of the Strike Force or during its transit to Hawaii. It was not until the attack on Pearl Harbor had commenced that radio transmissions began. The Strike Force maintained strict radio silence and thus there was no Allied foreknowledge of the attack through radio communications-despite revisionist claims to the contrary.
['Philip H. Jacobsen']
Radio Silence of the Pearl Harbor Strike Force Confirmed Again: The Saga of Secret Message Serial (SMS) Numbers