Once again, we will be honored by the presence of a Navajo Code Talker Joe Morris.

Come on out to this great event and meet a genuine American Hero. If you don't know about the Code Talkers, refer to the attachment which is a short blurb from Wikipedia.

NAVAJO CODE TALKERS
Philip Johnston proposed the use of Navajo to the United States Marine Corps at the beginning of World War II. The idea was accepted, and the Navajo code was formally developed and modeled on the Joint Army/Navy Phonetic Alphabet that uses agreed-upon English words to represent letters. As it was determined that phonetically spelling out all military terms letter by letter into words-while in combat-would be too time consuming, some terms, concepts, tactics and instruments of modern warfare were given uniquely formal descriptive nomenclatures in Navajo (the word for "potato" being used to refer to a hand grenade, or "tortoise" to a tank, for example).
A codebook was developed to teach the many relevant words and concepts to new initiates. The text was for classroom purposes only, and was never to be taken into the field. The uninitiated would hear truncated and disjointed strings of individual unrelated nouns and verbs. The code talkers memorized all these variations and practiced their rapid use under stressful conditions.

As the war progressed, additional code words were added on and incorporated program-wide, and in other instances, informal short-cut code words were devised for a particular campaign and not disseminated beyond the area of operation. To ensure a consistent use of code terminologies throughout the Pacific Theater, representative code talkers of each of the U.S. Marine divisions met in Hawaii to discuss shortcomings in the code, incorporate new terms into the system, and update their codebooks.
These representatives in turn would train the other code talkers who could not attend the meeting.

The Navajo code talkers were also deployed in the Korean War; the use of code talkers ended shortly into the Vietnam War.
Navajo code talkers, Saipan, June 1944

Non-speakers would find it extremely difficult to accurately distinguish unfamiliar sounds used in these languages.
Additionally, a speaker who has acquired a language during their childhood sounds distinctly different from a person who acquired the same language in later life, thus reducing the chance of successful impostors sending false messages.
Finally, the additional layer of an alphabet cypher was added to prevent interception by native speakers not trained as code talkers, in the event of their capture by the Japanese. A similar system employing Welsh was used by British forces, but not to any great extent during World War II; Welsh was used more recently in the Balkan peace-keeping efforts for non-vital messages.

Navajo in particular was an attractive choice for code use because few people outside the Navajo themselves had ever learned to speak the language and virtually no books in Navajo had ever been published. Outside of the language itself, the Navajo spoken code was not very complex by cryptographic standards and would likely have been broken if a native speaker and trained cryptographers worked together effectively. The Japanese had an opportunity to attempt this when they captured Joe Kieyoomia in the Philippines in 1942 during the Bataan Death March. Kieyoomia, a Navajo Sergeant in the U.S. Army, was ordered to interpret the radio messages later in the war.

However, since Kieyoomia had not participated in the code training, the messages made no sense to him. When he reported that he could not understand the messages, his captors tortured him . Given the simplicity of the alphabet code involved, it is probable that the code could have been broken easily if Kieyoomia's knowledge of the language had been exploited more effectively by Japanese cryptographers. The Japanese Imperial Army and Navy never cracked the spoken code, and high ranking military officers have stated that the United States would never have won the Battle of Iwo Jima without the secrecy afforded by the code talkers.