The ever increasing complexity of the world has changed how sustainment is conducted. The lines of communication have changed from internal and secure to external and contested. The footprint of Army forces has shifted from a large forward presence operating from numerous overseas bases to a continental United States-based, joint, integrated, and expeditionary force. The Army Operating Concept, Win in a Complex World, asserts that in order to win in this environment, Army forces must be able to "set the theater, provide strategic agility to the joint force, and maintain freedom of movement and action during sustained and high tempo operations at the end of extended lines of communication in austere environments."Setting the theater is a continuous shaping activity and is the responsibility of the geographic combatant command. As a result of the world becoming increasingly complex, U.S. forces must be able to establish the conditions in theater that are necessary to meet national objectives. The Army enables the geographic combatant command to set the theater by providing unique capabilities that include sustainment support.This article discusses from a doctrinal perspective what it means to "set the theater" and the role of the sustainment warfighting function in setting and supporting the theater using the joint phasing model. Analyzing and understanding setting the theater within the context of the joint phasing model is essential to understanding the role of Army sustainment in supporting unified actions.DEFINING SET THE THEATERAlthough "set the theater" is a relatively new phrase, the act of setting the theater is not. It serves as an umbrella term encompassing the activities associated with establishing the conditions for executing operations. Although the phrase appears in doctrinal literature, it is not officially defined in joint or Army doctrine.The Army Operating Concept for 2020-2040, published in 2014, added set the theater as an Army core competency and proposes that it be defined as the "actions taken to establish and maintain the conditions necessary to seize the initiative and retain freedom of action." This proposed definition is entirely too vague and does not meet the joint or Army criteria for official terms.Based on an extensive review of related current doctrine and other relevant material, set the theater is better defined as "the broad range of actions conducted to shape the operational environment, deter aggression, and establish the conditions in a theater of operations for the execution of strategic plans."THE JOINT PHASING MODELThe joint phasing model consists of six phases as shown in figure 1. The commander determines the applicable phases and the measures for determining when to transition from phase to phase. Generally, the end of one phase initiates the beginning of the next phase, but activities may begin in one phase and continue or conclude in a subsequent phase.The phasing model is not necessarily linear. For example, a commander may transition from the dominate phase to the stabilize phase in one area while remaining in the dominate phase in other areas. The decision to transition is based on predetermined criteria established by the commander. Additionally, the commander may shift back from the stabilize phase to the dominate phase if the situation changes and breaking the will of the adversary becomes necessary again.Phase 0 of the model is the shape phase. Shaping of the operational environment never ends because preparation and prevention are enduring activities in the national strategic and theater strategic plans. Phase I, the deter phase, consists of demonstrating national resolve and setting the conditions for projection of power and employment of the force. Phase II is the seize the initiative phase. Its emphasis is on applying the appropriate capabilities for combat operations or noncombat operations.Phase III, the dominate phase, focuses on achieving operational objectives or controlling the operational environment. Phase IV is the stabilize phase and concentrates on establishing security, restoring services, and helping the host nation to stabilize. Phase V is the enable civil authority phase and is focused on redeployment of the force and transferring control to civil authorities.Analyzing and understanding the operational environment is essential to applying the phasing model and setting the theater. Sustainment preparation of the operational environment assists commanders and staffs in identifying environmental factors and in refining the sustainment concept of support.The analysis of the operational environment is framed within the context of political, military, economic, social, information, infrastructure, physical environment, and time variables. Analysis within the context of these variables facilitates logisticians' understanding of the sustainment support needed to establish the proper conditions in theater for contingency operations designed to achieve the objectives described in national strategic guidance.NATIONAL STRATEGIC DIRECTIONSetting the theater is guided by national strategic direction, the Joint Strategic Planning System, and the Adaptive Planning and Execution System. National strategic direction ranges across all phases of the joint phasing model as shown in figure 2.Authoritative documents guiding set the theater include (but are not limited to) the National Security Strategy, National Defense Strategy, Unified Command Plan, National Military Strategy, and theater strategy.The National Security Strategy describes the overarching worldwide interests of the United States, and the National Defense Strategy describes how the armed forces will support the objectives of the National Security Strategy.The Unified Command Plan addresses the combatant commands' areas of responsibility and missions and provides other guidance. The National Military Strategy describes the national military objectives and how the armed forces will achieve them. The geographic combatant command develops the theater strategy, which links activities in theater with national strategic guidance.Although the Department of Defense is a highly capable organization, the military is only one element of national power, and setting the theater in order to achieve U.S. interests requires collaboration.WHOLE-OF-GOVERNMENT APPROACHSetting the theater involves a whole-of-government approach among the departments and agencies of the U.S. government. Whole-of-government initiatives include establishing bilateral or multilateral diplomatic agreements that grant U.S. forces access to the ports, terminals, airfields, and bases within an area of responsibility. They are needed to support future military contingency operations.For example, the Department of State and other governmental organizations conduct negotiations with other nations and establish agreements for host-nation support. The support negotiated can include, among many other things, sea and aerial ports of debarkation, terrain preparation for marshalling areas or bases, warehousing, communications, and logistics capabilities.Operation United Assistance is a recent example of the whole-of-government approach. During that operation, the Department of State, through the U.S. Agency for International Development, worked with the government of Liberia and the U.S. Africa Command to attain the agreements and resources needed to fight the Ebola virus disease in West Africa.The whole-of-government approach enables alliances, military partnerships, and the interoperability that optimizes force capabilities, reduces competing demands for resources, and maximizes capacities. Sustainment planning using the whole-of-government approach fills resource gaps by contracting services for water, storage, energy, and facilities. This approach aids sustainment planners as they try to operate with a minimal logistics footprint while still providing sufficient sustainment.SUSTAINMENT OPERATIONSA strategic priority of the Army is to be globally responsive and regionally engaged. Achieving this end requires Army service component commands and theater support forces that are capable of setting the theater in support of the combatant commander's plan.Sustainment support is joint, interdependent, and continuously conducted throughout the six phases of the joint phasing model. Once it has been determined that joint force capabilities are required, the combatant commander implements contingency operations plans and builds on the sustainment support begun in the previous phases.Sustainment planners support the joint force by conducting activities that include theater opening, port opening, Army support to other services, theater distribution, and reception, staging, onward movement, and integration (RSOI). Sustainment operations continue across all phases of the joint model.THEATER OPENINGTheater opening begins at the deter phase of the joint phasing model. It involves establishing and operating ports of debarkation (air, sea, and rail), a distribution system, and sustainment bases. Theater opening facilitates port throughput for the RSOI of forces within a theater of operations.Theater opening activities include the deployment of specific capabilities (security forces, port opening teams, and mission command structures) needed to attain host-nation support and to establish port operations required for receiving forces into the theater. Normally, an expeditionary sustainment command conducts the planning, preparation, and execution for theater opening operations for Army forces in theater.PORT OPENINGPort opening is a joint mission in which Army forces play a major role. The U.S. Transportation Command and its subordinate service component commands are responsible for managing port operations. The Air Force's Air Mobility Command is responsible for managing aerial ports of debarkation, and the Military Surface Deployment and Distribution Command is responsible for managing sea ports of debarkation.Army doctrine defines port opening as "the ability to establish, initially operate, and facilitate throughput for ports of debarkation to support unified land operations." The port opening process is considered complete when the supporting infrastructure needed for port operations has been established. Once ports are established and able to receive forces, the Army's sustainment commands organize and control the movement of forces to forward locations for integration with assigned forces.RSOIRSOI is the joint process used to deliver combat power to the joint force commander. Reception includes receiving and clearing personnel and equipment through the port of debarkation. Staging activities are conducted to organize the arriving forces and build them into capable units. Onward movement often includes host-nation support and delivers forces where they are needed.Integration follows onward movement and is complete when the receiving commander determines the unit is capable of performing its assigned mission. The theater sustainment command or expeditionary sustainment command provides mission command for reception, staging, and onward movement.SUPPORT TO THE OTHER SERVICESJoint interdependence is essential to sustainment operations. It reduces duplication of effort and competition for resources through the purposeful reliance of one service's forces on another service's capabilities to maximize the complementary and reinforcing effects of both. The combatant commander implements joint interdependence through directive authority for logistics and can assign the Army the task of providing common-user support to other services. Examples of support provided include common-user land transportation and common-user logistics. The Army may also enter into interservice support agreements with other services to obtain reimbursement for services provided.THEATER DISTRIBUTIONThe goal of theater distribution is to provide operational forces with the materiel and supplies needed to maintain the operational initiative. Establishing the theater distribution network is an essential part of sustainment support and is pivotal to obtaining freedom of movement and action.The Army is responsible for the theater leg of the distribution pipeline, so the Army sustainment commands provide mission command for the distribution process. The theater distribution system consists of four networks: physical, financial, informational, and communications.The physical network includes the means for distribution (airfields, roads, bridges, railroads, structures, pipelines) and the capabilities for supporting distribution operations. The financial network facilitates distribution operations by providing policies, processes, and systems for the use of fiscal resources.The informational network is the combination of all information systems that support theater distribution. The communications network links the complex elements of distribution. The combination of the four networks significantly affect the efficacy of the distribution system and the Army's ability to provide sustainment support to the theater.Winning in a complex environment requires Army forces capable of setting and supporting a theater. Army forces provide strategic land power to the joint force in all six phases of the joint phasing model, and Army sustainment forces facilitate freedom of movement and action during sustained and high-tempo operations.The Army's set the theater core competency consists of a broad range of actions that are conducted in order to shape the operational environment, deter aggression, and establish the proper conditions in a theater of operations for the execution of strategic, national, and theater plans. The Army's ability to set and support the theater is critical to achieving the goals established in national strategic guidance._____________________________________________________________________________________________________ Kenneth R. Gaines is the chief of the Joint Allied Doctrine Branch at the Combined Arms Support Command at Fort Lee, Virginia. He has a bachelor's degree in biology from Virginia Union University and a master's degree in microbiology from Virginia State University. He is a retired Medical Service Corps lieutenant colonel and a graduate of the Joint Course on Logistics, the Army Force Management Course, and the United Nations Logistics Course.Dr. Reginald L. Snell is the senior doctrine developer at the Combined Arms Support Command (CASCOM). He previously served in the Joint and Army Concepts Division, Army Capabilities Integration Center, at Fort Eustis, Virginia, and as the experimentation team chief in CASCOM's Sustainment Battle Laboratory. He is a retired Army officer and has a doctorate in education from Capella University. _____________________________________________________________________________________________________ This article was published in the November-December 2015 issue of Army Sustainment magazine.