ATP 2-01.3 constitutes current doctrine on how to systematically evaluate the effects of significant characteristics of the operational environment (OE) for specific missions. This publication— Describes how the commander and staff examine mission variables to understand how these variables may affect operations. - Discusses intelligence preparation of the operational environment (IPOE) as a critical component of the military decision-making process, how IPOE supports decision-making, and the integrating processes. - Facilitates a common understanding, foundational concepts, and methods of the IPOE process. The principal audience for ATP 2-01.3 is tactical Army commanders and staffs. Commanders and staffs of Army headquarters serving as a joint task force or a multinational headquarters also refer to applicable joint or multinational doctrine related to IPOE. Trainers and educators throughout the Army also use this publication. This manual applies to intelligence activities conducted outside the United States. Intelligence activities conducted inside the United States, as well as those that target U.S. persons and groups outside the United States, invoke additional requirements and intelligence oversight rules. To the extent any of the activities described in this publication are conducted inside the United States, or target U.S. persons or groups outside the United States, consult the judge advocate for assistance. ATP 2-01.3 applies to the Active Army, the Army National Guard/Army National Guard of the United States, U.S. Army Reserve, unless otherwise stated. The proponent of ATP 2-01.3 is the U.S. Army Intelligence Center of Excellence. The preparing agency is the Directorate of Doctrine and Intelligence System Training, U.S. Army Intelligence Center of Excellence, Fort Huachuca, AZ.