This policy directive provides guidance for planning and conducting defensive counterinformation (DCI) operations, the aerospace function through which the Air Force employs its defensive Information Operations (IO) capabilities. This policy applies to all military and civilian Air Force personnel, members of the Air Force Reserve, Air National Guard, DoD contractors, and individuals or activities under legal agreement or obligation with the Department of the Air Force. The success of aerospace operations depends on the Air Force's ability to access reliable information, effectively utilize information systems, and perform information functions despite adversarial attempts to exploit or deny those capabilities. The Air Force will employ comprehensive, integrated defensive counterinformation (DCI) operations to protect and defend Air Force information and information systems. DCI is a multi-discipline mission area impacting many functional areas. Air Force DCI capabilities include information assurance, operations security (OPSEC), counterintelligence, counter-deception, counterpsychological operations, and electronic protection. Effective DCI requires the full integration of numerous supporting activities to include intelligence and IO-related law enforcement efforts, as well as physical, personnel, industrial, and information security (e.g., document classification and control) measures. The Air Force will integrate DCI awareness, objectives and capabilities into strategy, plans, operations, acquisition and procurement, exercises, inspections, training, communications and computer architectures, systems development, and professional education. AFPD 10-20 is not intended to duplicate or interfere with the management of those functional aspects of DCI that are already working well; rather, it provides the policy basis for an overarching, integrated DCI program for the Air Force.