What is the US Secretary of Defense?
The United States Secretary of Defense is the civilian head of the Department of Defense, a sprawling government agency which deals with military matters. As head of the Department of Defense, the US Secretary of Defense advises the President of the United States on policy matters, and he or she also works with the Joint Chiefs of Staff, who command the branches of the United States military. This position in the United States government is widely regarded as critical, because the Secretary of Defense has a huge influence on the direction of American military policy.