In its October 1993 Bottom-Up Review of the nation’s defense needs, DOD, among other things, judged that it is prudent to maintain the capability to fight and win two nearly simultaneous MRCs. In the review, DOD also determined the forces, enhancements to force capabilities, and funding necessary to execute this element of the national military strategy. Since the Bottom-Up Review, DOD has conducted various studies to examine the two-MRC requirement. In an August 1994 memorandum, the Chairman of the Joint Chiefs of Staff authorized DOD to conduct the Nimble Dancer exercise. The primary objective of the exercise was to assess the capability of the programmed Bottom-Up Review force to fight and win two nearly simultaneous MRCs during different time periods, and the secondary objective was to identify critical issues for further resolution or study. The Chairman’s memorandum generally stated that the exercise would test the sufficiency of forces by examining various areas, such as lift, intelligence, and sustainment, and provide a forum for conducting sensitivity analyses. In preparing to conduct Nimble Dancer, DOD developed terms of reference and a study plan. These documents, among other things, identified various analyses for testing the sensitivity of game assumptions. They also established specific measures of effectiveness to evaluate each scenario, such as the level of risk, days of battle, and specific territory lost or gained. According to DOD officials, the terms of reference and study plan were draft documents that were never finalized or formally approved as official guidance. Rather, these documents were used to generate discussion among the participants about the types of analyses that might be conducted. They stated that other than the Chairman’s general memorandum, no official guidance governed the specific conduct of the war game. Nimble Dancer, conducted from November 1994 to July 1995, consisted of baseline computer modeling, separate analyses on selected two-MRC topics, and seminars to discuss modeling and other analytical results. The computer modeling simulated force deployment and combat in various two-MRC scenarios involving a North Korean invasion of South Korea and an Iraqi invasion of Kuwait. According to DOD, this modeling assessed the scenarios in the years 1997, 2001, and 2005. Seminar participants were mid- and senior-level military officers and DOD civilians, including the Secretary of Defense, the Chairman of the Joint Chiefs of Staff, and the commanders of selected combatant commands. Since conducting Nimble Dancer, DOD has continued to analyze issues related to the two-MRC requirement. Based on Nimble Dancer, DOD concluded that the United States can fight and win two nearly simultaneous MRCs in the 1997 and 2001-2005 time frames, provided that the force enhancements anticipated in the Bottom-Up Review are completed as programmed and that national command authorities make timely decisions at the onset of the first MRC.In reaching this conclusion, DOD identified several issues that it deemed critical to ensuring the success of U.S. forces. In press statements and congressional hearings, the Secretary of Defense and the Chairman of the Joint Chiefs of Staff said that Nimble Dancer tested and validated basic Bottom-Up Review assumptions, and they characterized the war game as extensive, intensive, rigorous, and robust. Nimble Dancer served as a means to promote interaction among DOD organizations and identify critical issues related to the two-MRC requirement. In Nimble Dancer, DOD included numerous modeling and analytical efforts that resulted in what officials described as an unprecedented sharing of data among participants. Officials told us these factors ensured a thorough discussion of the two-MRC scenario and related critical issues. Nimble Dancer participants represented many offices and levels within the defense community responsible for planning and executing the two-MRC requirement. For example, participants included representatives from the Office of the Secretary of Defense; the Joint Staff; unified commands; the Army, the Navy, the Air Force, and the Marine Corps; and defense agencies. Military officers from these organizations served as participants in the issues identification and senior officer phases of the war game. Participants from combatant commands included those with responsibilities for developing U.S. war plans for the MRCs addressed in Nimble Dancer. Additionally, the military’s highest ranking military and civilian officials participated in the war game. For example, the Secretary of Defense and the Chairman of the Joint Chiefs of Staff were among the participants in the final phase of the war game. According to DOD officials, the war game provided for continuity in that approximately 60 percent of the officials who participated in the Nimble Dancer 1997 assessment also participated in the 2001 and 2005 assessments. According to DOD officials, Nimble Dancer promoted the sharing of model assumptions and data, which was unprecedented. Models used in the war game, among other things, examined the execution of the conflicts, conduct of deployment, use of airpower, impact of chemical weapons, and employment of theater ballistic missile defense. According to DOD officials, for the first time, the Navy, the Air Force, and the Army exchanged detailed data on each other’s weapon systems for use in their respective service models. For example, the Navy, using data from both the Air Force (on fighters) and the Army (on helicopters), modeled a complete joint air campaign. In addition, DOD used contractors to perform modeling using Joint Staff inputs. For example, DOD contracted with BDM Federal, Inc., and the Johns Hopkins University Applied Physics Laboratory to perform modeling for chemical warfare and theater ballistic missile defense, respectively, because DOD believed their models could examine the issues in greater depth. BDM and Applied Physics Laboratory officials told us that they also shared information while performing their respective analyses. According to Nimble Dancer participants, the war game served as a useful tool for identifying and discussing critical issues for fighting and winning two MRCs. Such issues included the sufficiency of strategic mobility, timeliness of national level decision-making, sufficiency of combat and support forces to meet desired conflict end mitigation of the impact of chemical and biological warfare, impact of extracting forces from peace operations, effectiveness of intelligence capabilities, availability of Bottom-Up Review force enhancements, planning to optimize the apportionment of forces and lift assets for two mitigation of the impact of mine warfare threats, and mitigation of the impact of ballistic missile threats. In addition, Nimble Dancer led to follow-on Joint Staff studies of intelligence capabilities and the extraction of forces from peace operations. It should also be noted that DOD had previously identified some of these critical issues. For example, a DOD mobility study that preceded the conclusion of Nimble Dancer emphasized the importance of acquiring sufficient airlift and sealift assets and prepositioning equipment and supplies overseas. During Nimble Dancer, DOD used many key assumptions in modeling the two MRCs that were identical or similar to assumptions in the May 1994 Defense Planning Guidance (DPG), which implemented the Bottom-Up Review. These assumptions were generally favorable; that is, they minimized risks to U.S. forces and objectives. DOD officials originally considered performing analyses to test the sensitivity of several key assumptions to more adverse circumstances. However, because of guidance to adhere to the DPG and other factors, certain sensitivity analyses were not done. Furthermore, in some cases, the scope of the analyses that were performed was limited. These limitations precluded DOD from analyzing the robustness of U.S. forces to execute the two-MRC strategy under more adverse circumstances. Furthermore, DOD lost the opportunity to identify additional critical issues that could have emerged. We examined several key assumptions used in Nimble Dancer to determine the extent that they were derived from the DPG, were favorable, and were tested against more adverse circumstances. As discussed below, these assumptions involved national command authorities’ decisions on mobilizing reserves and activating the Civil Reserve Air Fleet; separation time (that is, the time between conflicts); warning times before enemy attack; and the location of MRC end states (that is, the point where hostilities cease). We focused on a particular two-MRC scenario that DOD said created the greatest risks to U.S. forces and objectives. Information on other assumptions appears in appendix I. In Nimble Dancer, DOD used DPG assumptions about the timing of the presidential selected reserve call-up authority and the partial mobilization authority. These assumptions appear favorable in that DOD assumed the national command authorities will decide very early in the scenario to mobilize reserves. According to the study plan, DOD considered performing sensitivity analyses on the mobilization of reserves to determine the timing and level that would be required to support two MRCs. However, as discussed later, DOD did not conduct these sensitivity analyses. In Nimble Dancer, DOD used DPG assumptions on when the national command authorities will activate the Civil Reserve Air Fleet—civilian aircraft that augment the military in wartime. These assumptions are again favorable because they assume that the national command authorities activate the fleet very early. According to the study plan, DOD considered conducting sensitivity analyses related to fleet activation to determine the timing and level that would be required to support two MRCs. These analyses would also have examined the economic impact of activation and the potential contribution of foreign airlines to move personnel. However, DOD did not conduct these sensitivity analyses. DOD officials cited a variety of reasons why they did not conduct certain sensitivity analyses. They stated that the Chairman requested that they adhere to the DPG as much as possible and to not use a worst-case scenario. The Chairman also requested that Nimble Dancer be completed by March 1995. Further, they said time and manpower constraints prevented them from doing all of the sensitivity analyses originally considered in the terms of reference and study plan and still generally meet the time frames set by the Chairman. For example, the Joint Staff requested modeling assistance from some DOD organizations that could not meet such requests due to competing work priorities. Finally, they said that if assumptions were deemed reasonable by most game participants, no sensitivity analysis was considered to be needed.