The National Defense Strategy is the foundation for DOD’s direction to the military services on planning their respective force structures. This strategy calls for the U.S. armed forces to be able to simultaneously defend the homeland; conduct sustained, distributed counterterrorist operations; and deter aggression and assure allies in multiple regions through forward presence and engagement. If deterrence fails, U.S. forces should be able to defeat a regional adversary in a large-scale multi-phased campaign, and deny the objectives of—or impose unacceptable costs on—a second aggressor in another region. According to the Army’s force development regulation, the Army seeks to develop a balanced and affordable force structure that can meet the requirements of the National Military Strategy and defense planning guidance tasks. The Defense Planning Guidance operationalizes the National Defense Strategy and provides guidance to the services on their use of approved scenarios, among other things, which serve as their starting point for making force structure decisions and assessing risk. These classified scenarios are used to illustrate the missions articulated in the National Defense Strategy, including the need to defeat one regional adversary while deterring a second adversary in another region, homeland defense, and forward presence. Drawing from the scenarios approved in the Defense Planning Guidance for 2017 through 2021, the Army derived a set of planning scenarios, arrayed across a timeline, that reflect these missions. Congress authorizes the number of personnel the Army is able to have in its active, Army National Guard, and Army Reserve components respectively. The Secretary of the Army—in consultation with the Director of the Army National Guard and the Chief of the Army Reserve— approves how the Army will allocate that end strength within each of the Army’s components. Between fiscal year 2011 and fiscal year 2018, the Army’s planned end strength is projected to decline by 132,000 positions (12 percent), from about 1.11 million soldiers in fiscal year 2011 to 980,000 soldiers in fiscal year 2018, as shown in figure 1. By fiscal year 2018, the individual components expect to be at the following projected end strengths: active (450,000), Army National Guard (335,000), and Army Reserve (195,000). As a result, the reserve component—which includes both the Army National Guard and the U.S. Army Reserve—will make up 54 percent of the Army’s planned end strength starting in fiscal year 2018; a proportion that is comparable to the size and allocation of Army forces across its components prior to the September 11, 2001, terrorist attacks. The Army implements its force development processes to make decisions about how to allocate end strength that has been authorized for each of its components, among other things. Taking into account resource constraints, the five-phase process entails determining organizational and materiel requirements and translating those requirements into a planned force structure of units and associated personnel, as illustrated in figure 2. During the fourth phase—the determination of organizational authorizations—the Army undertakes its annual Total Army Analysis (TAA) process, during which it determines how it will allocate its end strength among its units and manage risk. The TAA process is envisioned to help the Army allocate its end strength among its enabler units—those units that deploy to support combat forces—after initial decisions about the size of combat forces, other types of Army formations, and key enablers are made. The Army’s TAA regulation states that the Army will use force guidance, such as the defense planning guidance, to identify the combat unit structure that will be used as an input to TAA’s analysis of the Army’s enabler unit requirements. The Army also uses the results from its most recently concluded TAA as the starting point for the next TAA. For example, Army officials stated that the planned force structure documented in its October 2015 Army Structure Memorandum was an input for the Army’s ongoing TAA, examining force structure for fiscal years 2019 through 2023. The Army Structure Memorandum documents the force structure approved by the Secretary of the Army for resourcing and is an output of the Army’s TAA process. Army officials said that the Army concluded the quantitative analysis phase for this TAA in December 2015 and they expect that the Army will complete the qualitative analysis phase by June 2016. Army officials said that they have modified the TAA process substantially since the Army last issued its regulation and that an updated regulation that will cover TAA is pending final approval. Last updated in 1995, the Army’s TAA regulation describes the objectives and procedures of the TAA process, which includes documenting the Army’s total planned force structure and any unresourced unit requirements. Army officials said that the Army no longer documents unresourced unit requirements because senior leadership at the time the Army stopped tracking these requirements determined that it was not useful for force planning purposes. Additionally, the Army has expanded the inputs to its TAA process beyond those specified in its regulation to include other segments of its force structure and some enabler units that were not eligible for reduction or reallocation. For example, the Army has identified a minimum number of positions for its generating force—which includes units that enable the Army to train and safeguard the health of its soldiers—and during recent TAAs did not evaluate some types of enabler units for reduction or reallocation that were considered to be in high demand (such as its Patriot Battalions) and units that are considered to be critical to early phases of a major contingency (such as those that provide port opening capabilities). The Army prioritized retaining combat units, as well as other segments of its force structure, when planning to reduce its end strength to 980,000 soldiers and as a result will take proportionately more position reductions from its enabler units. are responsible for fighting enemy forces in a contested environment and include the Army’s Brigade Combat Teams (Armored, Infantry, and Stryker) and combat aviation brigades. to the Army’s combat units when they are deployed. They often provide critical support in early deployment (such as port opening), as well as for long-term sustainment (such as those that transport supplies or establish bases from which combat units can operate). Combat units are dependent on enabler units for long-term sustainment in theater and the Army generally deploys both types of units to meet operational demands. The Army prioritized retaining combat units and incorporated other considerations when planning to reduce its end strength to 980,000 soldiers. Army officials said that the Army used its force planning process to evaluate how it can best implement planned end strength reductions. This process—which is intended to link strategy to force structure requirements given available resources—included robust modeling and incorporated senior leaders’ professional military judgement. The Army incorporated its priorities at the beginning of this process, which influenced the planned force structure that the Secretary of the Army ultimately approved. Foremost, the Army sought to retain as many combat units as possible so that it could better meet the missions specified in DOD’s defense planning guidance and the Army’s classified scenarios as well as to account for near-term uncertainty. Additionally, the Army determined it needed to maintain a minimum number of positions in its generating force and its transients, trainees, holdees, and students accounts, based on separate analyses. Lastly, the Army sought to minimize the disruption to Army National Guard capabilities and reserve component unit readiness that resulted from reductions. Generating Force: Army organizations whose primary mission is to generate and sustain the operating force, including the Army’s Training and Doctrine Command—which oversees the Army’s recruiting, training, and capability development efforts—and Army Medical Command—which provides health and medical care for Army personnel. Trainees, Transients, Holdees, and Students: Active component soldiers not assigned to units are counted as part of the Army’s end strength, separately from its operating force and generating force. Soldiers in these accounts include soldiers in training, cadets attending military academies, injured soldiers, or soldiers en route to a new permanent duty station. Retaining combat units. According to Army officials responsible for TAA, Army leaders determined that it was important that the Army retain as many combat units as possible when assessing how to implement end strength reductions. In 2013, the Secretary of Defense announced the conclusion of the department-wide Strategic Choices and Management Review. As part of this review, DOD examined ways to obtain cost savings by altering the Army’s future force structure. According to Army officials, the Secretary of Defense’s review had, at one point, considered whether the Army could reduce its end strength to 855,000, which would correspond with a force structure of 36 BCTs, including 18 in the regular Army and 18 in the reserve component. Army leaders, reacting to what they considered to be unacceptable reductions, commissioned analyses to determine the end strength and number of BCTs the Army needed to execute the missions specified in defense planning guidance. The analysis determined that the Army should retain a minimum of 52 BCTs, including 30 in the active component, in order to best meet the missions specified in defense planning guidance. Ultimately, Army senior leaders decided to retain 56 BCTs based in part on these analyses as well as their assessment of global events and the potential for increased demand for BCTs. In retaining 56 BCTs in its force structure, the Army took additional steps to redesign its force, reflecting its priority to retain combat capacity. Specifically, the Army plans to eliminate 17 BCTs from its force structure relative to its fiscal year 2011 force (a 23 percent reduction in the number of BCTs). However, because the Army decided to redesign its BCTs by increasing its composition from a two maneuver battalion to three battalion formation, the Army estimates that it will be able to retain 170 maneuver battalions in its force structure—a net reduction of 3 battalions compared to fiscal year 2011 (less than 2 percent), as shown in table 1.