Section 233 of the National Defense Authorization Act for Fiscal Year 2014 required DOD to report on various regional BMD topics, including the eight specific elements presented in table 1, by June 24, 2014. DOD identified its current approach to regional BMD in the 2010 Ballistic Missile Defense Review Report. In that report, DOD stated it would match U.S. BMD strategies, policies, and capabilities to the requirements of current and future threats and use that information to inform BMD planning, budgeting, and oversight. DOD also noted that phased, adaptive approaches to BMD would enable a flexible, scalable response to BMD threats around the world by incorporating new technologies quickly and cost-effectively, and described the advantages of mobile BMD assets that can be readily transported from one region to another, over fixed assets. In addition, DOD indicated that new assets would undergo testing that enables assessment under realistic operational conditions, prior to deployment. Finally, DOD emphasized working with regional allies to strengthen BMD and its deterrent value. The 2010 Ballistic Missile Defense Review Report indicates that the United States would pursue a phased, adaptive approach to missile defense within each region that is tailored to the threats and circumstances unique to each region. An area of emphasis in the 2010 Ballistic Missile Defense Review Report was on the EPAA—the U.S. approach to regional BMD in Europe. In the 2010 Ballistic Missile Defense Review Report, DOD also discussed the development of regional phased, adaptive approaches to BMD in the Asia-Pacific and the Middle East. The 2010 report highlighted differences among the ballistic missile threat posed to each region, as well as the differences among the regional defensive arrangements that exist between the United States and its partners. In an August 2013 report on regional BMD issues, DOD stated that its process of working with regional allies and partners was well under way and included the participation, along with the United States, of some allies and partners in regional command and control centers that conduct BMD operations. In the Pacific, DOD noted that cooperation is most robust with Japan, that other allies and partners participate to varying degrees, and that allies and partners in the Asia-Pacific region generally have exhibited an increasing interest in enhanced cooperation with DOD. DOD’s August 2013 report also noted that in the Middle East the United States is working with a number of Gulf Cooperation Council States on a bilateral basis, including supporting the purchase of BMD systems through the Foreign Military Sales program. DOD’s regional BMD effort consists of a number of specific weapon systems or elements that compose the BMD system as a whole. They are the following: Command and Control, Battle Management, and Communications (C2BMC): a system that integrates individual BMD elements and allows users to plan BMD operations, maintain situational awareness and communications, and manage networked sensors. Army Navy/Transportable Radar Surveillance and Control Model 2 (AN/TPY-2) X-Band Radar: a sensor that tracks ballistic missiles in flight. Aegis BMD Weapons System: a ship-based weapon system that consists of a radar, software, and processors to track threat missiles and cue Aegis Standard Missile-3 (SM-3) interceptors. Aegis Ashore: a land-based version of the Aegis BMD interceptor system, which will employ Aegis BMD Weapons System upgrades and SM-3 upgrades as they become available. Standard Missile-3 (SM-3): a family of defensive missiles that intercept regional threat missiles of various ranges. Terminal High Altitude Area Defense (THAAD): a mobile, ground- based missile defense system that includes a fire control and communications system, a radar, interceptors, and other support equipment. Patriot Advanced Capability-3 (PAC-3): a mobile defense against short-range missiles. It is now operated and fielded by the U.S. Army and may be used in a variety of regional BMD approaches. According to DOD, various versions of these weapon systems are being deployed in Europe, the Asia-Pacific region, and in the Middle East, but the EPAA is the only regional approach described extensively in the 2010 Ballistic Missile Defense Review Report. To support Phase 1 of the EPAA for operations in Europe, by December 2011 MDA delivered an AN/TPY-2 X-band radar, an Aegis BMD ship with SM-3 Block IA missiles, and an upgrade to C2BMC. As we reported in March 2014,the EPAA are intended to provide improved integration and interoperability among sensors and interceptor systems, which would expand the area being defended, as well as improve the ability to defend against attacks involving a larger number of incoming missiles. Specifically, for Phase 2, MDA plans to deploy improved versions of the Aegis BMD Weapons System on ships and Aegis Ashore in Romania with the next generation of SM-3 interceptor, called SM-3 Block IB. MDA also plans to field improvements to C2BMC, upgrading an existing version in the 2015 time frame and fielding a new version in 2017. For Phase 3, MDA is developing further improvements to the Aegis BMD system, including a new version of the weapons system and new interceptor, called SM-3 Block IIA, as well as an additional Aegis Ashore installation in Poland and further improvements to C2BMC for fielding in 2018. Figure 1 depicts the weapon systems that DOD plans to deploy in and around Europe in support of the EPAA in its three phases. DOD, Report to Congress: Regional Ballistic Missile Defense. Compared to the statutory reporting requirements, DOD’s June 2014 regional BMD report addressed five of the eight required reporting elements, and partially addressed the remaining three elements. DOD addressed elements that describe the overall risk assessment from the Global Integrated Air and Missile Defense Assessment, the role of regional missile defenses in the homeland defense mission, the integration of offensive and defensive capabilities, and two elements on the roles and contributions of allies. DOD partially addressed the remaining three reporting elements, regarding the alignment of regional approaches to missile defense with combatant command integrated priorities, the concept of operations for EPAA, and the testing and development of key EPAA elements. Table 2 summarizes our assessment of DOD’s report. Additionally, through interviews with DOD officials and from our application of generally accepted standards that define a sound and complete defense research study, we found that DOD’s report did not include key details for some required reporting elements that we believe could have benefitted congressional defense committees’ oversight of DOD’s regional BMD programs. Generally accepted standards that define a sound and complete defense research study include that a report provide complete, accurate, and relevant information for the client and stakeholders. However, DOD’s report does not consistently meet this standard, based on GAO’s review. For example, the standards for the presentation of results state that findings should be complete and accurate, but we found that key information regarding the characterization of the testing and development of EPAA systems was incomplete. DOD’s June 2014 report could have provided additional details for several of the required reporting elements. Specifically: In support of element F, regarding integration of offensive and defensive capabilities, the report described some plans regarding implementation of the imperatives suggested in the Joint Integrated Air and Missile Defense Vision for 2020. We determined that DOD’s report met the statutory requirement to describe the manner in which enhanced integration of offensive and defensive capabilities will fit into regional missile defense planning and force structure assessments. Although not required, we found the report did not provide comprehensive information on how DOD will identify and address potential capability and capacity shortfalls in support of air and missile defense missions, nor did it provide a description of policies to increase cooperation among partners and allies, as emphasized by the Joint Integrated Air and Missile Defense Vision for 2020, which is information that provides more insight into how DOD manages regional BMD resources and risks. In support of elements G and H, regarding allied contributions to regional BMD, DOD’s report included some information that did not relate to regional missile defense and characterized a number of allied contributions as notional, which could misrepresent the extent to which particular allies and partners contribute to regional BMD. For example, the report mentions Denmark hosting an Upgraded Early Warning Radar in Greenland as an allied contribution to European missile defense, but that radar is used exclusively for supporting the homeland defense BMD mission. Additionally, the report did not include estimates of actual or potential cost savings derived from taking advantage of economies of scale or a reduced number of U.S. deployments due to allied capabilities. For instance, Japan’s effort to develop and deploy the Aegis BMD Weapon System on Japanese ships is mentioned by the report, but without concrete information on the effect that may have on U.S. resources. Appendix I highlights U.S. and allied contributions to regional BMD operations. Additionally, we determined that DOD’s report omitted key details regarding its approach to regional BMD for the three elements that it partially addressed in the report, regarding the combatant commands’ force structure and deployment options, concepts for operating with NATO, and the development of EPAA systems. We believe that by not including these details, although not required, DOD reduced the report’s usefulness to the congressional defense committees and to their oversight of DOD’s regional BMD programs. In support of element B, regarding the combatant commands’ deployment options, as stated earlier, we determined that DOD’s report partially addressed the required reporting element because it did not include key details about U.S. European Command’s and U.S. Pacific Command’s planned options to increase BMD capability in response to an imminent threat, nor did the report provide a comprehensive analysis regarding how the various regional approaches to BMD will meet combatant command integrated priorities.