The Department of Defense (DoD) relies on a global network of DoD and non-DoD infrastructure so critical that its unavailability could have a debilitating effect on DoD's ability to project, support, and sustain its forces and operations worldwide. DoD established the Defense Critical Infrastructure Program (DCIP) to assure the availability of mission-critical infrastructure. GAO was asked to evaluate the extent to which DoD has done the following: (1) incorporated aspects of DCIP into its exercises in the Transportation Defense Sector, and (2) developed DCIP training standards department-wide and made installation personnel aware of existing DCIP expertise. GAO examined a nonprojectable sample of 46 critical assets representing the four military services, five combatant commands, and selected installations within five defense sectors. GAO reviewed relevant DoD DCIP guidance and documents and interviewed cognizant officials regarding DCIP exercises, training, and awareness. GAO recommends that DoD do the following: (1) develop department-wide DCIP training standards and an implementation time frame, and (2) develop an effective means to communicate to installation personnel the existence and availability of DCIP expertise at the combatant command and military service levels. DoD concurred with both recommendations.