Who is the principal assistant to the President for all matters relating to the Department of Defense?

• A. Chairman of the Joint Chiefs of Staff
• B. Secretary of Defense
• C. National Security Advisor
• D. Vice President

Answer: (B)

The main idea is who leads the Department of Defense under civilian oversight. The Secretary of Defense is the President’s principal civilian adviser and head of the Department of Defense, responsible for all matters relating to the department, including policy, budgeting, and military readiness. This role ensures civilian control of the military while coordinating defense policy across the department and with other national security bodies. The other positions play important advisory roles but don’t serve as the top civilian administrator of the DoD: the Chairman of the Joint Chiefs of Staff is the senior military advisor, not the department head; the National Security Advisor coordinates overall national security policy, not the DoD; and the Vice President has broad duties but is not the DoD’s leader.