DOD operates six geographic combatant commands, each with an assigned area of responsibility (see fig. 1). Each geographic combatant commander carries out a variety of missions and activities, including humanitarian assistance and combat operations, and assigns functions to subordinate commanders. Each command is supported by a service- component command from each of the services. All of these component commands play significant roles in preparing detailed posture plans and providing the resources that the combatant commands need to execute operations in support of their missions and goals. DOD’s facilities are located in a variety of sites that vary widely in size and complexity. Some sites are large complexes containing many facilities to support military operations, housing, and other support facilities, while others can be as small as a single radar site. To develop common terminology for posture planning, DOD has identified three types of installations that reflect the large-to-small scale of DOD’s enduring overseas posture—main-operating bases, forward-operating sites, and cooperative security locations. Main-operating bases are overseas installations with relatively large numbers of permanently stationed operating forces and robust infrastructure, including family support facilities. Forward-operating sites are scaleable installations intended for rotational use by operating forces in lieu of permanently stationed forces that DOD would have to support. Because they are scaleable, they may have a large capacity that can be adapted to provide support for combat operations, and therefore DOD populations at these locations can vary greatly, depending on how they are used at any given time. Cooperative security locations are overseas installations with little or no permanent U.S. military presence, which are maintained with periodic U.S. military, contractor, or host-nation support. DOD populations at these locations can vary greatly, as they do at forward- operating sites, depending on how they are being used at any given time. A hierarchy of national and defense guidance informs the development of DOD’s global posture. The National Security Strategy, issued by the President at the beginning of each new Administration and annually thereafter, describes and discusses the worldwide interests, goals, and objectives of the United States that are vital to its national security, among other topics. The Secretary of Defense provides corresponding strategic direction in the National Defense Strategy. Furthermore, the Chairman of the Joint Chiefs of Staff provides guidance to the military through the National Military Strategy. The department has developed new guidance for global defense posture in numerous documents, principally the 2008 Guidance for Employment of the Force and the 2008 Joint Strategic Capabilities Plan. The Guidance for Employment of the Force consolidates and integrates planning guidance related to operations and other military activities, while the Joint Strategic Capabilities Plan implements the strategic policy direction provided in the Guidance for Employment of the Force and tasks combatant commanders to develop theater campaign, contingency, and posture plans that are consistent with the Guidance for Employment of the Force. The Theater Campaign Plan translates strategic objectives to facilitate the development of operational and contingency plans, while the Theater Posture Plan provides an overview of posture requirements to support those plans and identifies major ongoing and new posture initiatives, including current and planned military construction requirements. Figure 2 illustrates the relationships among these national and DOD strategic guidance documents. DOD is currently transforming its military posture in South Korea through a series of four interrelated posture initiatives, but has not estimated the total costs involved, or provided an analysis of alternatives for one initiative—tour normalization—that was initiated by the Commander, USFK that potentially could affect tens of thousands of DOD personnel and dependents and increase costs by billions of dollars. Although DOD has not fully estimated the total cost of its posture initiatives, we obtained USFK and Army estimates for each initiative, which were primarily focused on construction costs, which indicate the magnitude of costs will be significant—almost $18 billion in costs have been identified either to the Government of South Korea or to DOD through fiscal year 2020 (see table 1). The largest of these four initiatives and the primary long-term cost driver is tour normalization—extending the tour length of military service members and moving thousands of their dependents from the United States to South Korea. According to USFK officials, the decision to move forward with tour normalization was made to achieve certain USFK strategic objectives, such as to provide military commanders greater flexibility in how U.S. military forces assigned to South Korea are used and to improve the quality of life for military service members and their families. However, prior to making the decision to move forward with the tour normalization initiative, DOD did not complete a business case analysis that would evaluate the quantifiable and nonquantifiable benefits, advantages, or disadvantages of competing alternatives in order to identify the most cost-effective means to satisfy its strategic objectives. As a result, DOD is embarking on an initiative that involves moving thousands of U.S. civilians to South Korea and constructing schools, medical facilities, and other infrastructure to support them without fully understanding the costs involved or considering potential alternatives that might more efficiently achieve U.S. strategic objectives. Four major, interrelated initiatives that will affect posture are under way in South Korea. Two of these initiatives—the Yongsan Relocation Plan and the Land Partnership Plan—will consolidate U.S. military and civilian personnel from Seoul and sites north of Seoul, to a site south of Seoul. The third will establish and maintain United States military troop strength at 28,500 soldiers, and the fourth—tour normalization—will provide for 36-month accompanied tours (personnel who bring their families with them) for military personnel stationed in South Korea. In total, USFK officials have estimated the total DOD population in South Korea could increase from approximately 54,000 to 84,000 under these initiatives (see fig. 3). DOD has not estimated the full cost to implement these initiatives, but as of January 2011, DOD had identified approximately $18 billion in costs from the start of the initiative through fiscal year 2020 either to the Government of South Korea or to DOD, as described below. According to USFK and State Department officials, the United States and South Korea are currently consulting on the extent to which Special Measures Agreement funding will be applied to these initiatives. Yongsan Relocation Plan ($8.3 billion through fiscal year 2016). According to USFK officials, this is an initiative agreed to between the governments of the United States and South Korea in October 2004. The agreement involves the relocation of U.S. Army Garrison Yongsan, which contains the headquarters for U.S. 8th Army, USFK, Combined Forces Command, and the United Nations Command. This initiative will move most DOD personnel and their families—currently more than 17,000 people—from U.S. Army Garrison Yongsan, an installation located in the heart of Seoul, to U.S. Army Garrison Humphreys (Camp Humphreys), so that the land at Yongsan can be returned to South Korea. It is anticipated that South Korea will fund much of the construction costs for this initiative; USFK officials estimate that it will cost South Korea about $6.3 billion and the United States about $2 billion in construction costs through fiscal year 2016. Land Partnership Plan ($4 billion through fiscal year 2016). This realignment, agreed to between the governments of the United States and South Korea in March 2002, will move U.S. troops who are currently stationed north of Seoul farther south to Camp Humphreys, and the land they vacate is intended to be returned to South Korea. This move will involve about 7,000 to 8,000 servicemembers, primarily from the 2nd Infantry Division. The total estimated construction costs for the Land Partnership Plan are nearly $4 billion, about $3.4 billion of that to be funded by the United States. 28,500 U.S. troops ($0.245 billion through fiscal year 2016). According to the State Department, in 2008, the Presidents of the United States and South Korea agreed that U.S. troop strength would reach and be maintained at 28,500. USFK officials estimate that this initiative will cost the United States about $245 million during the 5-year period of fiscal years 2012 through 2016 ($140 million in military construction and $105 million in operation and support costs). DOD defines dwell time as the period of time between the release from involuntary active duty and the reporting date for a subsequent tour of active duty pursuant to 10 U.S.C. § 12302. Such time includes any voluntary active duty performed between two periods of involuntary active duty pursuant to 10 U.S.C. § 12302. consideration for back-to-back non-accompanied deployments. Tour normalization would reduce uncertainty for service members and their families, and affirm the United States commitment to the U.S.-Korean alliance and the region. It enables a more adaptive and flexible U.S. and combined-force posture on the Korean peninsula to strengthen the alliance’s deterrent and defense capabilities and long-term capacity for regional and global defense and security cooperation, according to the Commander’s Narrative Assessment. DOD has not finalized an implementation schedule for tour normalization as DOD continues to evaluate alternative implementation schedules and associated costs. As of September 2010, USFK officials estimated that the total DOD population in South Korea was approximately 52,800, including 11,600 dependents. One approach developed by USFK officials for implementing tour normalization called for completing the construction of facilities and movement of dependents to South Korea by 2020 except for the facilities and dependents associated with service members at Kunsan Air Base (the Air Force has yet to decide if tour normalization will be implemented at Kunsan Air Base). Under that schedule, initial steps to implement tour normalization, such as increasing the number of accompanied tours in South Korea, were expected to be completed in fiscal year 2011, when USFK officials estimated the total DOD population in South Korea would be about 54,000.