Complex sentence: Enders and Anderson are told that, because evidence shows captured Navajos are always tortured to death to get the code, it cannot fall into enemy hands, implying that they are to kill their code talkers if capture is imminent.
Split into simpler sentences: Enders and Anderson are shown evidence that captured Navajos are tortured to death to get the code and instructed that it cannot fall into enemy hands. This implies that they are to kill their code talkers if capture is imminent.