From Secrecy News:
DEFENSE INTELLIGENCE AGENCY MISSION AND FUNCTIONS
The functions and responsibilities of the Defense Intelligence Agency (DIA) are detailed in a 27-page directive that has been newly re-issued by the Department of Defense.
"DIA shall satisfy the military and military-related intelligence requirements of the Secretary and Deputy Secretary of Defense, the Chairman of the Joint Chiefs of Staff, and the DNI, and provide the military intelligence contribution to national foreign intelligence and counterintelligence."
See "Defense Intelligence Agency (DIA)," DoD Directive 5105.21, March18, 2008: