Why did General Vogel believe that the Navajo were the best suited of all the American Indians groups to serve as code talkers?

General Vogel believed that the Navajo were the best suited to serve as code talkers due to their unique language, which was complex and unwritten, making it difficult for enemies to decipher. Additionally, their cultural background and understanding of military strategy allowed them to effectively communicate and adapt under pressure. The Navajo's strong sense of loyalty and bravery further contributed to their effectiveness in this role during World War II.