The position was a member of the President 's Cabinet until 1947 , when the Navy , Army , and newly created Air Force were placed in the Department of Defense and the Secretary of the Navy was placed under the Secretary of Defense . The Secretary of the Navy was until 1947 a member of the President 's Cabinet , when the Navy , Army , and newly created Air Force were placed in the Department of Defense and the Secretary of the Navy was placed under the Secretary of Defense .