Marine Corps Doctrinal Publication (MCDP) 2, Intelligence, and Marine Corps Warfighting Publication (MCWP) 2-1, Intelligence Operations, provide the doctrine and higher order tactics, techniques, and procedures for intelligence operations. MCWP 2-6, Counterintelligence, complements and expands on this information by detailing doctrine, tactics, techniques, and procedures for the conduct of counterintelligence (CI) operations in support of the Marine airground task force (MAGTF). The primary target audience of this publication is intelligence personnel responsible for the planning and execution of CI operations. Commanders, planners, and other personnel who use the results from CI operations or provide support to them should also read this publication. MCWP 2-6 describes aspects of CI operations across the spectrum of MAGTF, naval, joint and multinational operations, including doctrinal fundamentals, equipment, command and control, communications and information systems support, planning, execution, security, and training. MCWP 2-6 provides the information needed by Marines to understand, plan, and execute CI operations in support of the MAGTF across the spectrum of conflict. MCWP 2-6 supersedes FMFM 3-25, Counterintelligence, dated 22 September 1992.