Abstract : The Department of Defense (DOD) requested about $6.1 billion in fiscal year 2010 for new unmanned aircraft systems (UAS) and for expanded capabilities in existing ones. To support ongoing operations, the Air Force and Army have acquired a greater number of larger systems. GAO was asked to determine the extent to which (1) plans were in place to account for the personnel, facilities, and communications infrastructure needed to support Air Force and Army UAS inventories; (2) DOD addressed challenges that affect the ability of the Air Force and the Army to train personnel for UAS operations; and (3) DOD updated its publications that articulate doctrine and tactics, techniques, and procedures to reflect the knowledge gained from using UAS in ongoing operations. Focusing on UAS programs supporting ongoing operations, GAO reviewed the services' program and funding plans in light of DOD's requirements definition and acquisition policy; interviewed UAS personnel in the United States and in Iraq about training experiences; and reviewed joint, multiservice, and service-specific publications.