DOD Instruction 4151.20 requires the armed services to apply a process to determine their core capability requirements—that is, to identify what core capabilities are required and what workload would be necessary to enable them to sustain these core capabilities at the depots. DOD Instruction 4151.20 describes a series of mathematical computations and adjustments that the armed services are required to use to compute their core capability requirements and to identify the workload that needs to be planned to support these requirements. Also, the instruction requires that the armed services identify the weapon systems required to execute the Joint Chiefs of Staff contingency scenarios, which represent plans for responding to conflicts that may occur in the future. After systems are identified, the armed services compute annual depot maintenance capability requirements for peacetime, in direct labor hours, to represent the amount of time they will regularly take to execute required maintenance. An armed service may determine that repair capabilities for certain systems maintained at the depots are so similar that they share common base repair processes that can effectively satisfy the repair requirements of other systems. During this process of identifying the systems for which they will be required to maintain repair capabilities, DOD Instruction 4151.20 requires that the armed services organize and aggregate their capability data by categories of equipment and technologies known as work breakdown structure categories. The work breakdown structure category is a grouping of work associated with DOD’s weapon systems and equipment. DOD uses these categories to organize data on its various core capability requirements and workloads to manage and report on its core capabilities. There are 11 categories at the top level—”first level”—of the work breakdown structure. A first-level category summarizes information for an entire type of system or equipment. Table 1 shows the 11 first-level categories of the work breakdown structure. A first-level category can be broken down into second-level subcategories, which are the major elements that make up the system or equipment in the first-level category. For example, the first-level category for Aircraft can be broken down into the second-level subcategories for Airframes, Aircraft Components, and Aircraft Engines, which are major elements that make up an aircraft. The second-level subcategories can be further broken down into third-level subcategories, which are subordinate elements that make up the major elements in the second- level categories. For example, the second-level subcategory for Airframes is further divided into the third-level subcategories—different types of airframes, such as Rotary, Fighter/Attack, or Bomber. The subcategories can be further broken down to the lowest-level element of the system. Lower-level categories are subcategories of the eleven first-level work breakdown structure categories. DOD refers to these levels as “levels of indenture.” The work breakdown structure can be expressed at any level of detail down to the lowest-level part, such as a bolt. Table 2 shows an example of the top three levels of the work breakdown structure for Aircraft. The instruction requires the armed services to identify their core capability requirements and the amount of available planned workload within the work breakdown structure categories and subcategories. DOD Instruction 4151.20 requires each DOD Component that performs depot maintenance to report biennially to OSD its core capability requirements and planned workload, in accordance with a tasking memorandum issued for each reporting cycle. The instruction includes a worksheet called the “core submission worksheet” that the components are to complete and submit to OSD. The worksheet calls for information to be organized by the work breakdown structure to various subcategory levels, mostly at the second level of subcategories. Appendix III provides a table listing these categories and subcategories. On October 5, 2015, OSD issued the tasking memorandum for the 2016 Biennial Core Report, which directs the armed services and the Missile Defense Agency to use DOD Instruction 4151.20 as basic guidance and includes further guidance on how to meet the requirement under Section 2464 to report this information to Congress. The memorandum augments the core submission worksheet by adding another column for the estimated costs of performing the planned workload at the first-level of work categories. The instruction and tasking memorandum also require the armed services to provide additional information when reporting shortfalls in planned workloads. If an armed service does not have sufficient workload to sustain the required level of capability that has been identified, a shortfall exists; in other words, the military depots have not been assigned sufficient depot maintenance workload to enable them to sustain their identified core capabilities. For example, an armed service may have identified 10,000 direct labor hours of core capability requirements for ground vehicles but have only 4,000 hours of anticipated depot maintenance work for ground vehicles. This armed service will have a workload shortfall of 6,000 hours. The instruction requires that the armed services report on shortfalls by providing a description of those shortfalls and a plan to address them to accompany the core submission worksheet, but it does not require that the shortfalls be calculated in the core submission worksheet. The Missile Defense Agency (MDA) was created in 2002 to develop a variety of systems, known as elements—including sensors, interceptors, command and control, battle management, and communications—to enable the warfighter to destroy enemy missiles before they can reach their targets. The ultimate goal is to integrate these various elements to function as a single system: the Ballistic Missile Defense System (BMDS). Once BMDS capabilities are developed that are useful to the warfighter, the management and some funding responsibility for the operation and sustainment of the capability is to be transferred to a lead service within the armed services. In 2003, MDA recommended and DOD approved the transfer of one system element, Patriot Advanced Capability–3 (PAC–3) program, to the Army. The PAC-3 was transferred to the Army because MDA had completed the initial development of this element and the Army, as the lead service, would now be responsible for managing the production, operation and sustainment of the PAC-3. According to MDA officials, to date, no other elements of the BMDS have transferred to the armed services. These officials also stated that MDA is responsible for the management, funding, production, operation, and sustainment of these elements and has been providing maintenance through contractor logistics support. For its 2016 Core Report, DOD included MDA as a reporting agency because, according to OSD, the BMDS developed by MDA is used to respond to contingency operations and has been identified as a core capability. To support the data in the Core Report, MDA provided information on three of the five elements of the BMDS in its core submission worksheet: 1. Aegis Ballistic Missile Defense – includes ship- and land-based ballistic missile defense capabilities using a radar, command and control, and Standard Missile-3 interceptors. The Navy was designated as the lead service in 2006. 2. Army Navy/Transportable Radar Surveillance – forward-based, land-based radar to provide additional advance warning of ballistic missile launches. The Army was designated as the lead service in 2006. 3. Terminal High Altitude Area Defense – a mobile, ground-based system to defend against short- and medium-range threats using a battery that consists of interceptors, launchers, a radar, and fire control and communication systems. The Army was designated as the lead service in 2006. According to MDA officials, they included these three system elements in their core submission worksheet because these elements are in use by the warfighter. MDA did not include the following two system elements in its core submission worksheet: 4. Command and Control, Battle Management and Communications – a globally deployed system of hardware—workstations, servers, and network equipment—and software that links and integrates individual elements, allowing users to plan ballistic missile defense operations, see the battle develop, and manage networked sensors. MDA developed this system in 2002. 5. Ground-Based Midcourse Defense – defends against intermediate- and intercontinental-range ballistic missiles by using ground-based interceptors that consist of a booster and a kill vehicle, plus a ground system that includes launch, communications, and fire control capabilities. The Army was designated as the lead service in 2006. According to MDA officials, they did not include these two system elements in their core submission worksheet because these elements are considered developmental programs and are not yet considered safe and suitable for use by the warfighter. DOD’s 2016 Core Report to Congress complied with two of the three required reporting elements of Section 2464—core capability requirements and planned workload. It partially complied with the third element, because it included information on shortfalls and mitigation plans, but it did not provide detailed explanations of all shortfalls and mitigation plans, as shown in table 3 below. Additionally, DOD included MDA as a reporting agency in its 2016 Core Report but did not report accurate information for it. Lastly, reporting agencies did not always provide accurate data for the Core Report because they do not have clear guidance on issues such as how to report additional depot workload performed that has not been identified as a core requirement, accurately capture inter-service workload, calculate shortfalls, and estimate cost of planned workload. DOD’s 2016 Core Report complied with the first two elements in Section 2464—to provide information on core capability requirements and planned workload. As requested by OSD to support the Core Report, the armed services provided data on their core capability requirements, organized by lower-level elements of the eleven first-level categories of the work breakdown structure. The report included the required information on core capability requirements—expressed in direct labor hours—at the first-level category of the work breakdown structure, for each of the armed services. As reported in DOD’s 2016 Core Report, DOD’s total core capability requirements are about 58.5 million direct labor hours, as shown in table 4.