Secretary of Defense; Secretary of Defence
Official title for the head of a defense department, typically in the US or other countries. Used in news and formal contexts.
The Secretary of Defense announced a new policy at the press conference.
国防大臣 is used for the defense minister in a parliamentary system (e.g., Japan's 防衛大臣), while 国防長官 is more typical for the US Secretary of Defense.
Compound of 国防 (national defense) and 長官 (secretary, director-general).