What concept involves protecting communications systems from unauthorized access?

The correct choice, COMSEC, refers to Communications Security, which encompasses measures taken to protect communications systems from unauthorized access, interception, and exploitation. It ensures the confidentiality, integrity, and availability of information transmitted over communication networks. COMSEC includes various practices such as encryption, frequency hopping, and secure transmission methods that safeguard sensitive communications.

Understanding the necessity of COMSEC is crucial for maintaining operational security in military and defense environments, where unauthorized access to communication could lead to critical information breaches and jeopardize missions.

In contrast, the other concepts such as Emissions Control focus on limiting emissions of electromagnetic energy to avoid detection, while Emitter Management deals with the control of radar and other active sensors. The Eagle Eye Protocol is less recognized within the framework of communications security and does not pertain directly to the protection of communication systems.