Here is an important document that details what role the DIA has. Department of Defense Directive 5105.21 (March 18, 2008)
The United State’s Department of Defense (DoD) has its very own Intelligence Agency. The Defense Intelligence Agency (DIA) is not a common household name, and rarely receives much press. Their function (from wikipedia):
DIA’s mission is to provide timely and objective military intelligence to warfighters, policymakers, and force planners. It is considered to be a member of the Intelligence Community. The director of DIA is the main adviser to the United States Secretary of Defense and the Chairman of the Joint Chiefs of Staff on matters related to military intelligence.
