What is a major risk if communications security (COMSEC) measures are not taken?

The correct answer relates to the potential vulnerabilities in military communications. If communications security (COMSEC) measures are not implemented or are inadequate, sensitive information can be intercepted, read, or manipulated by adversaries. This jeopardizes operational security and can lead to mission failure, compromised strategies, and potential loss of life. In military operations, maintaining the confidentiality and integrity of communications is crucial to protecting forces and ensuring that missions can be executed without undue risk from enemy actions.

The other options, while they touch on different aspects of military operations and communication, do not highlight the risks associated with a lack of COMSEC. Enhanced strategic planning and increased trust are desirable outcomes but do not directly relate to the negative consequences of insecure communications. Similarly, better mission outcomes are usually the result of effective planning and secure communication, but without COMSEC measures, these outcomes can be severely hindered or completely undermined.