Presented for exceptionally distinguished performance of duty contributing to national security or defense of the United States. The decoration is awarded only at the highest levels of the military while assigned to a joint activity. The medal may also be awarded to other senior officers whose direct and individual contributions to national security or defense are recognized as being so exceptional in scope and value as to be equivalent to contributions normally associated with positions encompassing broader responsibilities. It is the United States's highest peacetime defense award. Normally, such responsibilities deserving of the Defense Distinguished Service Medal are held by the most senior officers such as the Chairman and Vice Chairman of the Joint Chiefs of Staff, the Chiefs and Vice Chiefs of the Services, and Commanders and Deputy Commanders of the Unified Commands whose duties bring them into direct contact with the Secretary of Defense and other senior officials. This decoration takes precedence over the Distinguished Service Medals of the separate services and is not to be awarded to any individual for a period of service for which an Army, Navy, Air Force or Coast Guard Distinguished Service Medal is awarded.