what does the secretary of defense do
Report Abuse. The Secretary of Defense is the principal defense policy advisor to the President and is responsible for the formulation of general defense policy and policy related to all matters of direct and primary concern to the DoD, and for the execution of approved policy.ecretaries of Defense have multiple duties related to the defense of our nation. If you want specific details, go to the whitehouse.gov website and locate either the name or picture of our current Secretary of Defense Robert Gates.