In the previous Wuerker cartoon, AndyLit makes a very stupid unqualified statement.
… Yes, the Japanese had a pretty good idea that it [Navajo code-talker language] was Navajo. This is why they tortured a Navajo named Joe Kieyoomia (1919–1997). He was captured in the Philippines and on the Bataan Death march. Later, he survived Nagasaki, too. He was a member of the New Mexico 200th Coast Artillery.
They first tortured him because they thought he was Japanese-American.* After several months, they accepted that he was Navajo.*
[Yeah, torture really showed the Japanese the truth, huh?]
Then, later, they came to him with a list of words (that they had tried to write down, so they could repeat what they were hearing on the radios), and asked him what they were.
He could confirm it was lists of Navajo words, but it was nonsense to him. 《He was not trained in the memorized code that had been developed in San Diego, in 1942; 421 were trained in the code》 Then they tortured him, and that ended any attempt to really break the code. Without a willing Navajo to work with, progress on the code-breaking project was stalled for a long time.
[Another win for torture! Err, well, maybe not…]
The difficult consonants, vowels, and the tonal structure made it impossible for most untrained people to even transcribe. The Japanese had been good at breaking every code before that.
Kieyoomia was in the Japanese POW camps for 43 months.
as related by Eric Painter on Quora.com Check out the references there.