Which publication contains information about the security of military communications?

The publication that contains information about the security of military communications is ACP 122. This document, known as the Allied Communications Publication, specifically addresses the procedures and standards for ensuring secure communication within military operations. It provides guidelines on various aspects of military communications, including encryption, transmission security, and protective measures necessary to safeguard sensitive information during communication.

Understanding the context of this publication is crucial as it directly impacts the security protocols that military personnel must follow to maintain the integrity and confidentiality of their communications. In contrast, the other choices pertain to different areas; for instance, FM 21-100 focuses on soldier training, AR 190-51 relates to physical security of army installations, and ATTP 5-19 deals with risk management, none of which specifically targets the security aspects of military communications as ACP 122 does. Thus, the relevance of ACP 122 in the context of military communications security makes it the correct choice.