The National Defense Strategy is DOD’s primary strategy document, providing a foundation for all other strategic guidance in the department. The National Defense Authorization Act for Fiscal Year 2017 required DOD to develop a national defense strategy and update it at least once every 4 years and, during the years without an update, to assess the implementation of the strategy and whether any revision is necessary. The National Defense Strategy replaces the Quadrennial Defense Review, which the Armed Services Committees concluded had become too slow and ineffective to provide relevant strategic direction to the department. For each new strategy, DOD is required to identify, among other things: DOD’s strategic priority missions; the force structure, readiness, posture, and capabilities needed to support the strategy; and major investments required by the strategy. A separate provision in the act also established a Commission to assess the 2018 National Defense Strategy. The provision required the Commission to review the assumptions, missions, force posture and structure, and risks associated with the strategy. Congress expressed continued interest in DOD’s strategy implementation and assessment in the John S. McCain National Defense Authorization Act for Fiscal Year 2019, which included several provisions related to these matters. The National Defense Strategy falls under the President’s National Security Strategy, which outlines the overarching security strategy for the federal government. The National Defense Strategy is above the National Military Strategy, which provides more detailed military direction. Figure 1 provides the hierarchy and description of key U.S. strategic guidance documents. Organizations across DOD play a role in providing analytic support to senior leaders as they make force structure decisions to support the National Defense Strategy. Table 1 provides a summary of the organizations with key roles and responsibilities for providing analytic support to senior leaders making force structure decisions. DOD established its approach, Support for Strategic Analysis (SSA), in 2002 to provide analytic support to DOD senior leaders as they deliberate strategy and budget matters and to support evaluations of force structure needs across the joint force. SSA is structured to do this by providing a common set of assumptions for various military threats that form the basis for further analysis across the department. DOD guidance states that SSA is intended to provide a common starting point for the exploration of various approaches to address the threats. DOD guidance further states that analyses should provide senior leaders with insights on the relative risks of various operational approaches and force structures. Senior leaders would then have a basis to weigh options, examine tradeoffs across the joint force, and drive any force structure changes necessary to meet the strategy. For more information on the origin of SSA, see the sidebar below. Origin of Support for Strategic Analysis DOD officials told us that the department developed what became SSA because then Secretary of Defense Donald Rumsfeld was frustrated by the lack of objective measures to compare competing force structure proposals. During the 1990s, each service developed its own analytic process and assumptions for assessing force structure needs to develop requirements for budget submissions. Each service’s analytic process tended to favor its preferred force structure and operational approach. DOD officials stated that the lack of a common analytic starting point for all of the services also meant that senior leaders had difficulty getting beyond debates about the services’ respective assumptions during discussions on force structure priorities. As a result, the Secretary of Defense had no objective basis by which to decide whether, for example, a Navy proposal to buy more ships or an Air Force proposal to buy more fighter aircraft was the best way for the department to use its limited resources to support strategic priorities. SSA is led by OUSD (Policy), the Joint Staff, and CAPE—collectively referred to as the Tri-Chairs. DOD guidance assigns each Tri-Chair responsibility for creating one of three increasingly detailed products for a variety of military threats that, taken together, comprise the common starting point for additional analysis of that threat. The resultant SSA product library is then available to the services and other DOD organizations for further analysis. DOD guidance notes that the threats SSA products address are examples of the types of threats U.S. joint forces are expected to be able to address with acceptable risk. However, the guidance states that the forces described in the products are not intended to constitute DOD’s force structure requirements. Instead, analysis using these products is intended to help senior leaders establish force structure requirements that balance risk across a range of threats, within fiscal constraints. Table 2 identifies the three SSA products that are intended to form the common starting point for analysis for a given plausible threat, along with the lead Tri-Chair for each product type. According to DOD guidance, the military services are to support the Tri- Chairs in developing the SSA products and, according to DOD officials, are the primary users of these products. The guidance requires that the services use SSA products as common starting points for studies evaluating their force structure needs for implementing the defense strategy and supporting their budget development, among other things. Although the starting points are common across the department, each service uses its own analytic process to evaluate its specific force structure needs for implementing the strategy and supporting its budget development (see app. I for further details on each service’s analytic process). The services may examine any plausible threat in the SSA library that they believe may help them understand their force structure needs. However, the 2018 National Defense Strategy identifies several key threats and the principal priorities for the department that the services must prioritize when developing their force structures. Specifically, the unclassified summary of the strategy calls for the department to increase and sustain investments towards the long-term strategic competitions with China and Russia, and to concurrently sustain its efforts to deter and counter rogue regimes such as North Korea and Iran, defeat terrorist threats to the United States, and consolidate gains in Iraq and Afghanistan with a more resource-sustainable approach. Further, budget guidance—in particular the Defense Planning Guidance—directs each service on which threats it must focus as part of its budget development process. Figure 2 provides a generalized overview of how the SSA process was designed to operate. SSA has not provided senior leaders with the analytic support they need to evaluate and make fully informed decisions regarding the force structure needed to implement the National Defense Strategy. DOD has recognized this and attempted to reform SSA for several years, including exploring alternative options for providing senior leaders with better decision-making support. However, DOD has not fully developed these approaches and it is unclear whether they will provide the analytic support needed. To date, SSA has not provided the analytic support senior leaders need to evaluate and determine the force structure required to implement the defense strategy. DOD senior leaders have documented concerns with SSA in relevant guidance. For example, DOD’s 2016 Defense Analytic Guidance stated explicitly that there were cracks in the department’s analytic foundation, many of which originate within SSA. Further, CAPE and the Joint Staff had disengaged from the SSA process by this time but, as of September 2018, the services were still using SSA products for their force structure analyses and budget development. Based on our analysis, we believe that SSA has not yielded the analytic support that it was intended to provide owing to three interrelated and persistent challenges: (1) cumbersome and inflexible products, (2) limited analysis that tends not to deviate from the services’ programmed force structures and has not tested key assumptions, and (3) an absence of joint analysis evaluating competing force structure options and cross- service tradeoffs. DOD has not kept the SSA products complete and up to date because they are cumbersome and inflexible. DOD guidance states that SSA products are to be common starting points for analyses, including key threats identified in strategic guidance. DOD guidance also states that SSA products should retain consistency with DOD strategy and current intelligence and should incorporate operational approaches effective at mitigating future threats. Credible independent analysis of an issue requires a detailed, well-understood, up-to-date common basis for that analysis. As of September 2018, DOD’s library of products was incomplete and outdated. Specifically, the Detailed View was not available for any of the threats, and Joint Staff officials told us they stopped producing joint CONOPS through SSA in 2015. Moreover, the Joint Staff retired all of the existing SSA CONOPS in March 2018 because they were outdated and/or not aligned with the 2018 National Defense Strategy—though they were still available for the department to access. Service officials also told us that many of the approved Defense Planning Scenarios and CONOPS for the key threats identified in the 2018 National Defense Strategy do not reflect up-to-date military objectives and adversary capabilities. Additionally, the 2018 National Defense Strategy outlines a new force posture and employment model that could have major implications for future CONOPS. However, DOD is still developing these concepts and, as such, they are not yet reflected in any SSA products. Specific details on the status of key SSA products were omitted because the information is classified. One of the key reasons DOD did not keep the products complete and up to date was that developing and approving highly detailed and complex SSA products was cumbersome, taking a significant level of effort and time. Tri-Chair officials told us that developing the CONOPS and Detailed View, in particular, was difficult because there was a desire to gain consensus with all of the stakeholders and because the services wanted these products to have high fidelity detail in order to run their campaign models. For example, CAPE and Joint Staff officials told us that it took between 1 and 2 years to build and approve the Detailed View for one threat scenario. The officials added that the level of detail included made the product inflexible and difficult to vary. CAPE and Joint Staff officials agreed that this product became far too detailed and time-consuming and used a substantial amount of the department’s analytic capacity. As a result, the officials told us that CAPE abandoned building additional Detailed Views in 2012. The lack of agreed-upon details about the forces required has had other effects. For example, OUSD (Policy) and Joint Staff officials told us that the services still wanted the comprehensive information that the Detailed View was supposed to provide for use in their campaign models. Without CAPE producing Detailed Views, the officials noted that some of the detailed information migrated into the higher level CONOPS, making developing and analyzing that product more difficult and time-consuming as well. However, all four military services told us that they need and continue to use the SSA products—specifically, the Defense Planning Scenarios and CONOPS—to support program and budget formulation. Service officials also told us they have adapted CONOPS, as individual services or with other services, to better reflect the operational environment (e.g., updating intelligence estimates on adversary capabilities). However, CAPE and OUSD (Policy) officials told us that this results in the services’ analyses no longer being common and comparable across the department. The John S. McCain National Defense Authorization Act for Fiscal Year 2019 reiterates that OUSD (Policy) must, in coordination with the other Tri-Chairs, develop planning scenarios by which to assess joint force capabilities, among other things. Until the Tri-Chairs determine the analytic products needed and the level of detail that is sufficient to serve as a common starting point but also flexible enough to allow for variation of analysis, and ensure these products are updated, the military services will likely continue to generate budget requests based on analysis that is not comparable. As DOD’s 2016 Defense Analytic Guidance noted about the fiscal year 2017 budget review, the lack of a common basis for their analysis hampers the department’s ability to understand the relationship between future warfighting risks identified in analysis and the services’ programmatic decisions. Although DOD’s guidance stated that SSA will facilitate a broad range of analysis exploring innovative force structure approaches for mitigating future threats identified in the strategy, SSA has not done so. Innovative force structure approaches could include, for example, alternative CONOPS and deviations from programmed forces. The 2018 National Defense Strategy stated that DOD’s operational approach largely dates from the immediate post-Cold War era when U.S. military advantage was unchallenged and the threats were rogue regimes, which is no longer the case. OUSD (Policy) officials told us that SSA CONOPS also reflect this outdated approach that depends on overwhelming force for success, which is unrealistic against advanced adversaries. Similarly, DOD’s 2016 Defense Analytic Guidance called for SSA to emphasize analyzing and assessing risk against key threats rather than on defending predetermined force levels or capabilities. Rather, the 2018 strategy stated that the department must relentlessly pursue innovative solutions and devise insurmountable dilemmas for future adversaries and that incrementalism or evolutionary progress is inadequate. However, Tri-Chair and service officials told us the services have been reluctant to conduct or share these types of boundary-pushing analyses through SSA for fear that they will jeopardize their forces or limit their options. Tri-Chair officials also told us that the services have leveraged their participation in developing SSA products to ensure their favored major force structure elements are included in the common starting point. Joint Staff officials noted that they were able to do this because SSA did not constrain what force structure the services could use for their analysis. That is, if the force structure was programmed, they could use it because the goal was to overwhelm the adversary. However, by not significantly deviating from the starting points, the services were able to ensure that their analytic outcomes support the need for the already- programmed force. Additionally, several questionable assumptions underpin the analysis. Sensitivity analysis examines the effects that changes to key assumptions have on the analytic outcome and are helpful to understand risk. It can therefore provide insight to decision makers of how risk levels would change if conditions did not match the assumptions. However, Tri-Chair officials told us that the services, using SSA products as a starting point, generally have not conducted sensitivity analyses on key operational assumptions or on factors that may not be static (or at least have some uncertainty) and, if varied, may raise or lower the risk of completing assigned tasks or missions. According to these officials, as well as our past work, certain questionable assumptions have not been analyzed through sensitivity analysis as part of SSA. For example, all four services tend to assume that their readiness for a conflict will be high, consistent with the level directed in guidance. However, we reported in 2018 that at the individual service level, the military services continue to report readiness challenges and readiness rebuilding is anticipated to take 4 years or more. Specific details of service-specific assumptions that are problematic were omitted because the information is classified. The services have been reluctant to independently examine a broad range of innovative force structure options and conduct sensitivity analysis on key operational assumptions through SSA because, according to service officials, due to competing priorities they believe they can generally only affect marginal changes in their budgets from year to year and have limited analytic capacity. Service officials noted how the majority of their service’s budget each year is constrained by must pay bills, including personnel costs, supporting existing force structure, established contracts, sustaining the industrial base, and statutory mandates. As such, unless directed to by senior leaders, service officials told us that they typically do not use their limited analytic resources to conduct sensitivity analysis or explore alternative approaches. The sensitivity analyses they have been directed to conduct have generally been focused on smaller force structure changes, but have provided useful insights. For example, the Air Force conducted an analysis for its fiscal year 2019 budget request of how risk would be affected with various F-35 buy-rates and investments in munitions and base defense. The Air Force found that it could reduce risk by keeping its F-35 buy-rate steady instead of increasing it and could use the resulting savings to bolster its munitions stocks. DOD stated in its 2016 Defense Analytic Guidance that SSA is not adequately exploring innovative approaches to meet future challenges, and called for OUSD (Policy) to identify key operational assumptions for the services to use to conduct sensitivity analyses. However, the direction provided by the department has thus far been limited and has generally not provided specific guidance requiring the services to explore a range of innovative force structure approaches or identified key assumptions on which the services must conduct sensitivity analyses. For example, the three Defense Planning Scenarios updated in 2018 for the purposes of analysis in support of the fiscal years 2020 and 2021 budget requests included a number of parameters for further analytic exploration. However, the guidance encourages, but does not require, the services to conduct these analyses. As previously discussed, officials said the services are reluctant to conduct or share this analysis and are unlikely to do so without specific direction. As a result, SSA analysis largely reflects the services’ programmed force structures and has not driven any significant changes to force structure or resource allocation within DOD and lacks credibility with senior leaders, as documented in DOD guidance. Until DOD provides specific guidance requiring the services to explore a range of innovative force structure approaches relevant to the threats identified in the 2018 National Defense Strategy, including identifying key assumptions for sensitivity analyses, DOD senior leaders may not have full visibility into the risks in the joint force’s ability to execute the missions set out in the National Defense Strategy. A key stated goal of SSA was to create a common analytic foundation so that the services’ force structures could be evaluated as a joint force—as it would fight. However, SSA has not resulted in this type of joint analysis. Specifically, DOD guidance states that SSA is intended to facilitate the comparison and evaluation of competing force structure options and cross-service tradeoffs. DOD guidance also states that assessments of the aggregate capacity of the joint force can provide an analytic foundation to identify risk and understand tradeoffs across competing demands for the force. According to the services, SSA products provide a valuable resource and are critical to informing programmatic decisions. However, DOD’s 2016 Defense Analytic Guidance noted that there was a dearth of joint analysis at the operational and strategic levels; the department lacks a body or process to conduct or review joint force analysis; and the department’s SSA efforts were focused on developing, versus analyzing, the common starting points. Accordingly, it reiterated the need for SSA to free up time and resources to conduct joint analysis and review competing analyses. Tri-Chair officials told us that DOD currently compares and makes decisions on force structure options primarily through the budget process; however, such budget reviews are typically limited to specific areas of interest. The officials added that program and budget review is not the best place to evaluate joint force structure tradeoffs because the kinds of issues examined in the budget process are more limited in scope and generally do not include comprehensive cross-service comparisons. Lacking joint analytic capability to assess force structure needs could be problematic as the department moves forward to implement the 2018 National Defense Strategy. The John S. McCain National Defense Authorization Act for Fiscal Year 2019 directed OUSD (Policy), in coordination with the other Tri-Chairs, to conduct assessments of the capabilities of the joint force to achieve required objectives. However, Tri-Chair officials also told us that, as of 2018, there was not a mechanism in place for DOD to routinely assess joint force needs and force structure tradeoffs across the military services. As previously discussed, in 2016 this was identified as an issue, and limited progress has been made since then to ensure adequate joint analysis to support senior leader decision-making. Further, OUSD (Policy) officials told us that SSA has not been responsive to senior leaders because it has not provided timely and comprehensive answers to important questions that only joint analysis can provide, such as the extent to which the joint force can successfully meet a campaign’s overall objectives (e.g., win the war) or the extent to which cross-service tradeoffs would affect a specific campaign. As a result, force structure decisions in the department based on SSA have remained largely relegated to marginal changes through program and budget review, according to DOD. The department’s gap in a joint analytic capability is particularly problematic in light of the National Defense Strategy’s call for urgent change at a significant scale and recent proposals by the services to greatly expand their force structure—including the Navy’s plan to grow the fleet by as much as 25 percent and the Air Force’s plan to grow squadrons by 24 percent. Based on our discussions with officials and our analysis, there are a number of different options the department has for conducting such joint analyses, including establishing a separate body with these capabilities or specifying the organizational responsibilities and processes for conducting these comparisons and analyses. Until the department has an approach for conducting joint analyses or comparing competing analyses, DOD senior leaders will not have a robust joint analytic foundation to rely on to evaluate competing force structure options and cross-service tradeoffs. The department has recognized that SSA has shortcomings and made repeated efforts to address them, including specific intervention and supplemental guidance promulgated in 2014 and 2016. However, Tri- Chair officials told us that these prior efforts fell short, and the department’s struggles with SSA led to two of the three Tri-Chairs disengaging from the process—CAPE in 2012 and the Joint Staff in 2015. The Tri-Chairs agree that DOD continues to need a process and products that are current, more responsive to senior leader needs, and able to provide insights on alternative approaches and force structures that span the joint force. In addition, Joint Staff officials noted that SSA was too focused on force sizing, which is not consistent with the 2018 National Defense Strategy’s focus on innovation, modernization, and readiness. In order to address this, the Joint Staff is pursuing an alternative approach to SSA that would largely eliminate a separate formal analytic process. Instead, the Joint Staff believes that the Tri-Chairs and the services can address senior leader needs more efficiently by continuing to execute their existing statutory roles and responsibilities within their own individual organizations in lieu of SSA. Since 2016, the Joint Staff has reinvigorated its own analytic capability to support the Chairman of the Joint Chiefs of Staff and other senior DOD leaders, according to Joint Staff officials. Although officials from other DOD organizations have supported the Joint Staff’s reinvigoration of its analytic support, they told us that this approach is focused on the Chairman’s responsibility rather than on wider departmental needs and does not address key shortfalls in providing analytic support to senior leaders, including the need for a common, flexible starting point. Further, the Joint Staff’s alternative approach would rely on CAPE’s analysis in the budget process as the culminating point for final DOD force structure decisions. CAPE officials told us that the program review can assist DOD leadership in optimizing relatively limited changes to DOD’s force structure by evaluating service budget submissions and identifying alternatives for consideration. However, budget cycle time constraints mean that little analysis occurs within program review and, as a result, program review relies on the foundational analysis SSA was intended to provide. As such, CAPE’s annual program review is inadequate for comprehensively examining needs and making major tradeoffs across the joint force, according to the officials. Finally, the department originally created SSA as a separate analytic process to address a shortfall not addressed by key DOD entities pursuing their statutory responsibilities. The Tri-Chairs have also undertaken an effort to identify an alternative approach to SSA. Specifically, shortly after the new strategy was released in 2018, CAPE initiated a Tri-Chair “blank slate” review of DOD’s analytic process in order to thoroughly review—without preconceived solutions— how to best provide analytic support to senior leaders. According to Tri- Chair officials, this effort is in the early stages of development and has not yet identified solutions to the challenges that hampered SSA or documented any aspects of a new approach. While the department’s recognition of the challenges confronting SSA is promising, the two efforts underway to identify alternatives to SSA are not complete and it is unclear the degree to which these efforts will address the challenges that have been long-standing with SSA. Addressing these challenges is critical to being able to provide needed information for senior leaders to make decisions on how best to implement and execute the National Defense Strategy. The 2018 National Defense Strategy calls for the department to make difficult choices to prioritize what is most important to field a lethal, resilient, and rapidly adapting joint force needed to address the growing threats to U.S. security. It also emphasizes that this environment demands analysis that accepts uncertainty and complexity and can drive innovation among rapidly changing threats. To prepare the joint force for the threats identified in the strategy, the department’s leadership needs to be supported by timely and comprehensive analyses. However, SSA—DOD’s current approach for providing such analytic support—has not provided the timely and comprehensive analyses that senior leaders need to make informed decisions about the joint force structure needed to implement the National Defense Strategy. Senior leaders have documented in relevant DOD guidance that there are cracks in the department’s analytic foundation, many of which originate with SSA. This is due in part to highly detailed and complex products that are difficult to produce and lack flexibility to analyze, insufficient guidance to overcome the interests of the services to protect their force structure equities, and the lack of a joint analytic capability. Congress, in the John S. McCain National Defense Authorization Act for Fiscal Year 2019, required OUSD (Policy), in coordination with the other Tri-Chairs, to develop joint force objectives and conduct assessments of the joint force’s capability to meet those objectives. The department has demonstrated a desire to fix SSA’s deficiencies but has thus far been unable to overcome these challenges. Without determining the analytic products needed and updating them, issuing specific guidance requiring alternatives and key assumptions to be fully analyzed, and developing an approach for conducting joint analysis, DOD may not be providing its leaders with the analytic support they need to prioritize force structure investments that would best manage risk and address the threats outlined in the National Defense Strategy. We are making three recommendations to DOD as it reevaluates its analytic approach. The Secretary of Defense should ensure that OUSD (Policy), the Joint Staff, and CAPE—in consultation with the services—determine the analytic products needed and the level of detail that is sufficient to serve as a common starting point but flexible to allow for variation of analysis to support senior leader decisions, and update these products to reflect current strategy and intelligence estimates, as well as the anticipated operational approaches needed to address future threats. (Recommendation 1) The Secretary of Defense should ensure that OUSD (Policy) provide specific guidance requiring the services to explore a range of innovative force structure approaches relevant to the key threats identified in the National Defense Strategy, including identifying key assumptions on which the services must conduct sensitivity analyses. (Recommendation 2) The Secretary of Defense should establish an approach for comparing competing analyses and conducting joint analyses for force structure to support senior leaders as they seek to implement the National Defense Strategy. This could include establishing a separate body with these capabilities and/or specifying the organizational responsibilities and processes for conducting these comparisons and analyses. (Recommendation 3) We provided a draft of the classified version of this report for review and comment to DOD. That draft contained the same recommendations as this unclassified version. In its written comments (reproduced in app. II), DOD concurred with our three recommendations and noted that the department has begun to address the recommendations with its new Defense Planning and Analysis Community initiative. We also received technical comments from DOD, which we incorporated as appropriate. DOD provided comments on its concurrence with the three recommendations. In its comments on the first recommendation, DOD suggested that we revise the recommendation to include that the Tri- Chairs consult with the services as they implement the recommendation. Throughout our report, we identified the important role the services play in providing analytic support to senior leaders, including supporting the development and use of the analytic products that provide the foundation of analysis in the department. As such, we agree with DOD’s proposed revision and have incorporated it to further clarify the services’ important role. In its comments on the second and third recommendations, DOD advised that we replace the term “force structure” with “force planning” to ensure that different audiences understand that we are referring to force sizing, shaping, capability, and concept development. DOD correctly stated that we were using the term “force structure” in a broad sense. However, the term force planning is not interchangeable with force structure because force planning is the act of analyzing and determining force structure needs. In order to provide further clarification, we added a note in the body of the report stating that when we refer to force structure analysis, it includes the force planning elements identified by DOD (i.e., force sizing, shaping, capability, and concept development). The department also provided some general comments on our report. Specifically, DOD noted that it has reservations about some of the report’s content because at times it seems to reflect statements based on particular organizational perspectives. DOD therefore requested that we acknowledge that Support for Strategic Analysis (SSA) suffered from poor implementation rather than being fundamentally unsound. However, DOD also stated that our report outlined that SSA failed due to overall suboptimal management and unwieldy stakeholder execution, and that the resulting failure to present analysis in a timely and responsive fashion impeded the flow of quality information to senior leaders. We believe that the three interrelated challenges we identified in our report adequately reflect that SSA faced significant challenges in being implemented as intended. Further, we identified that there are a broad range of views within the department on what the challenges have been and how to best address them. We continue to believe that it is important that these views be presented in the report and have attributed them as appropriate. DOD also commented that we reference a desire within the department to gain “consensus” amongst SSA stakeholders, but thought that “coordinated” was a more appropriate word than consensus, since consensus was not required to produce SSA products. In the report, we did not state that consensus was required, but noted that DOD officials told us that the desire for consensus amongst SSA stakeholders was a contributing factor in making SSA products cumbersome and inflexible. Further, DOD’s 2016 Defense Analytic Guidance similarly identifies the “degree of consensus” as an area requiring SSA process reform. DOD’s final comment noted that the military services used SSA products and routinely conducted sensitivity analysis for their internal use. We recognize in the report that the services conduct a variety of analyses, including some sensitivity analyses. However, we also identify important assumptions that remain untested. As we reported, service officials told us that they have limited analytic capacity and so tend not to do sensitivity analyses on topics unless specifically directed to do so. Further, we noted that the services have been reluctant to conduct or share boundary- pushing analyses through SSA for fear that they will jeopardize their forces or limit their options. As a result of this and the other challenges we identified in this report, the quality of SSA products and analysis and the information provided to senior leaders to inform decision-making has been limited. As DOD moves forward with implementing our recommendations, it will be important that it take the necessary steps to ensure that any future analytic processes thoroughly examine and test key assumptions and look across the joint force. Doing so would help ensure any new process can overcome the constraints that limited the effectiveness of SSA. We are sending copies of this report to congressional committees; the Acting Secretary of Defense; the Acting Under Secretary of Defense for Personnel and Readiness; the Under Secretary of Defense for Policy; the Chairman of the Joint Chiefs of Staff; the Director, Cost Assessment and Program Evaluation; the Secretaries of the Army, the Navy, and the Air Force; and the Commandant of the Marine Corps. In addition, the report is available at no charge on the GAO website at http://www.gao.gov. If you or your staff have any questions about this report, please contact me at (202) 512-3489 or pendletonj@gao.gov. Contact points for our Offices of Congressional Relations and Public Affairs may be found on the last page of this report. GAO staff who made key contributions to this report are listed in app. III. Each military service has its own process for determining its force structure requirements using national strategies, defense planning guidance, and Support for Strategic Analysis (SSA) products. Below is a description of each service’s process as of September 2018. Army. The process the Army uses for identifying its force structure needs has two phases: (1) “Capability Demand Analysis” where the Army uses SSA-approved Defense Planning Scenarios to determine how large a force is needed to support the National Defense Strategy and with what mix of units and (2) “Resourcing and Approval” where senior Army leaders assess each capability within the Army to determine where reductions and growth need to occur given available resources. The Secretary of the Army approves changes to force structure through the end of the Future Years Defense Program in a decision memorandum, and these decisions are documented in an Army Structure Memorandum. Navy. The process the Navy uses for identifying its force structure needs begins with the identification of the Navy’s steady-state, peacetime operations requirements. The Navy then conducts campaign and warfighting risk analyses to determine the force’s ability to fight and win SSA-approved Defense Planning Scenarios. Specifically, the Navy tests each force element against the most stressing Defense Planning Scenario, which provides the Navy with its battle force warfighting—to include surge—requirements. These warfighting requirements are compared with steady-state requirements and the more stressing forms the basis of the Force Structure Assessment, which establishes the long-term force structure goals of the Navy’s 30-year shipbuilding plan and aviation plan, and informs the programming and budget processes, among other things. Air Force. The Air Force has a largely decentralized process for identifying its force structure needs that is part of the Air Force’s annual budget development process. The Air Force manages its activities and budgets primarily across 12 Core Functions—the broad capabilities the Air Force provides to the combatant commanders. Much of the force structure analysis that informs budget decisions is also conducted at the Core Function level. The Air Force also conducts occasional leadership-directed studies on future capability needs in certain mission areas (e.g., air superiority needs beyond 2030) as well as a unified risk analysis of its entire force structure that is intended to inform senior leader budget decisions. The Air Force is currently revising its approach to better integrate its capability development and analysis earlier in the process. Marine Corps. The Marine Corps conducts service-level reviews of its force structure at the discretion of the Marine Corps Commandant. A Force Structure Review is typically directed as a result of major service-level issues, such as end strength or capability changes. Marine Corps Force 2025 is the most recent comprehensive assessment of the Marine Corps’ force structure and organization. This was a three-phased effort that relied on one Defense Planning Scenario to develop alternative force structures and evaluate them against a near-peer adversary. The Commandant directed this review to emphasize growing information warfare capabilities. The Marine Corps also conducts Force Optimization Reviews, which are biennial reviews designed to optimize the current and planned future force, taking into consideration new and emerging requirements. Table 3 shows some of the comparable elements of the individual service force structure development processes. In addition to the contact name above, Patricia Lentini, Assistant Director; Nicolaas Cornelisse; Martin De Alteriis; Carly Gerbig; Mae Jones; Amie Lesser; Shahrzad Nikoo; Carol Petersen; and Alex Winograd made key contributions to this report.

Summary: DOD's 2018 National Defense Strategy continues the department's shift toward focusing on the challenges posed by major powers—China and Russia. The strategy concludes that DOD must pursue urgent change at a significant scale and starkly warns that failure to properly implement the strategy will rapidly result in a force that is irrelevant to the threats it will face. To implement the change DOD envisions, senior leaders must have quality information. Senate Report 115-125 includes a provision for GAO to review DOD's analytic approach for informing force structure decisions to implement the National Defense Strategy. This report assesses, among other things, whether DOD's analytic approach has provided senior leaders with the support needed. GAO reviewed DOD guidance, assessed whether DOD was meeting the objectives identified in its guidance, and interviewed agency officials. This is an unclassified version of a classified report issued in February 2019. Information that DOD deemed classified has been omitted. The Department of Defense's (DOD) analytic approach has not provided senior leaders with the support they need to evaluate and determine the force structure necessary to implement the National Defense Strategy. DOD's analytic approach—Support for Strategic Analysis (SSA)—is used by the services to evaluate their force structure needs and develop their budgets. However, GAO found that SSA has been hindered by three interrelated challenges: Products are cumbersome and inflexible. Although DOD guidance states that SSA products are to be common starting points for analysis on plausible threats, including threats identified in strategic guidance, DOD has not kept the products complete and up to date in part because they were highly detailed and complex and therefore cumbersome to develop and analyze. Analysis does not significantly deviate from services' programmed force structures or test key assumptions. Although DOD's guidance states that SSA should facilitate a broad range of analysis exploring innovative approaches to mitigate threats identified in the strategy, the services generally have not conducted this type of analysis because guidance has not specifically required the services to do so. DOD lacks joint analytic capabilities to assess force structure. Although DOD guidance states that SSA is intended to facilitate the comparison and evaluation of competing force structure options and cross-service tradeoffs, the department has not conducted this type of analysis because it lacks a body or process to do so. DOD efforts to revise its analytic approach are in the early stages and have not yet identified solutions to these challenges. Moreover, DOD has attempted reforms in the past without success. Without a functioning analytic process that addresses the above challenges, senior leaders do not have the analytic support they need to prioritize force structure investments that would best manage risk and address the threats outlined in the National Defense Strategy. GAO recommends that DOD (1) determine the analytic products needed and update them, (2) provide specific guidance requiring the services to explore a range of alternative approaches and force structures, and (3) establish an approach for conducting joint force structure analysis across the department. DOD concurred with the recommendations and noted the department has begun addressing them.