United States General Accounting Office

GAO Report to the Chairman and Ranking

Minority Member, Committee on

National Security, House of

Representatives

June 1996 BOTTOM-UP REVIEW

Analysis of DOD War

Game to Test Key

Assumptions

G O A

years

1921 - 1996

GAO/NSIAD-96-170

GAO United States

General Accounting Office

Washington, D.C. 20548

National Security and

International Affairs Division

B-272119 

June 21, 1996

The Honorable Floyd D. Spence

Chairman

The Honorable Ronald V. Dellums

Ranking Minority Member

Committee on National Security

House of Representatives

As you requested, we reviewed the objectives, methodology, and results of

the Department of Defense’s (DOD) war game Nimble Dancer, which

assessed the ability of U.S. forces to fight and win two nearly simultaneous

major regional conflicts (MRC). We also identified assumptions or data

used in Nimble Dancer pertaining to several specific areas, such as

readiness, threat, and force availability. This report, an unclassified

version of our May 1996 classified report, presents our observations on the

objectives, methodology, and results of the exercise, and appendix I

provides details on the specific areas of interest.

Background 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

Page 1 GAO/NSIAD-96-170 Bottom-Up Review
B-272119 

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.

1

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.

Results in Brief DOD statements that Nimble Dancer tested basic Bottom-Up Review

assumptions through intensive and extensive war-gaming suggest a more

rigorous level of analysis than occurred during the exercise. Nimble

Dancer was a useful forum for promoting interaction among DOD

organizations and in identifying critical issues in fulfilling the two-MRC

requirement. However, Nimble Dancer used many of the same favorable

1

The national command authorities consist of the President and the Secretary of Defense or their duly

deputized alternates or successors.

Page 2 GAO/NSIAD-96-170 Bottom-Up Review
B-272119 

assumptions contained in DOD guidance implementing the Bottom-Up

Review. Although DOD originally considered examining the sensitivity of

certain key assumptions, this type of analysis in some cases was not done,

and in other cases its scope was limited. Furthermore, DOD did not fully

examine the impact of certain critical issues. For example, DOD’s analyses

of chemical warfare and the extraction of forces from peace operations

were limited in scope and did not fully identify the impact of these issues

on MRCs. Also, DOD deferred detailed analyses of the sufficiency of support

forces and intelligence capabilities to other studies. The limited sensitivity

analysis of certain key assumptions and limited analysis of some critical

issues precluded DOD from analyzing the robustness of the programmed

Bottom-Up Review force to meet the two-MRC requirement under more

adverse circumstances. In addition, DOD lost opportunities to acquire

additional information about the impact of specific critical issues on U.S.

capabilities.

Military judgment is an integral part of any DOD war game or analysis.

During Nimble Dancer, DOD relied on the professional military judgment of

participants to reach its conclusions, especially where modeling and other

analytical results were not available.

All of these factors—favorable assumptions, limited sensitivity analysis,

the lack of full analysis of certain critical issues, and heavy reliance on

military judgment in some cases where analysis was lacking—should be

considered in evaluating DOD’s conclusions that Nimble Dancer tested and

validated Bottom-Up Review assumptions.

Nimble Dancer

Promoted Interaction

Within DOD and

Identified Critical

Issues

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.

Game Participants

Included Experienced

Officials From Key

Organizations

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

Page 3 GAO/NSIAD-96-170 Bottom-Up Review
B-272119 

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.

Collaborative Modeling

Efforts Described as

Unprecedented

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.

Participants Say Critical

Issues Were Identified

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

states,

• mitigation of the impact of chemical and biological warfare,

• impact of extracting forces from peace operations,

• effectiveness of intelligence capabilities,

Page 4 GAO/NSIAD-96-170 Bottom-Up Review
B-272119 

• availability of Bottom-Up Review force enhancements,

• planning to optimize the apportionment of forces and lift assets for two

MRCs,

• 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.2

Nimble Dancer

Testing of Key

Assumptions Was

Limited

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.

2

DOD Mobility Requirements Study Bottom-Up Review Update, March 28, 1995.

Page 5 GAO/NSIAD-96-170 Bottom-Up Review
B-272119 

Reserve Mobilization In Nimble Dancer, DOD used DPG assumptions about the timing of the

presidential selected reserve call-up authority3

 and the partial mobilization

authority.4

 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.

Activation of the Civil

Reserve Air Fleet

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.

Amount of Separation

Time Between MRCs

In Nimble Dancer, DOD assumed a separation time between the beginning

of the two MRCs similar to that in the DPG. According to some Nimble

Dancer documents, this separation time between MRCs could be

3

Under 10 U.S.C. 12304, the President can activate up to 200,000 reservists for up to 270 days without a

declaration of war or other national emergency.

4

Under 10 U.S.C. 12302, the President can activate up to one million reservists for up to 2 years to meet

the requirements of a war or other national emergency.

Page 6 GAO/NSIAD-96-170 Bottom-Up Review
B-272119 

interpreted as advantageous. Combatant commands, specifically the

Pacific Command and the Central Command, estimate different separation

times.

According to the terms of reference and study plan, DOD considered

conducting sensitivity analyses to use combatant commands’ views on

separation time to determine whether U.S. forces could meet requirements

using different assumptions. During Nimble Dancer, there were two

analyses that varied separation time from the baseline—one by U.S.

Central Command representatives participating in the game and another

by DOD’s Office of Program Analysis and Evaluation. According to

command and DOD officials, these analyses were conducted in a relatively

short period of time and were not structured or intended to

comprehensively examine the implications of shortening the separation

time. The scope of these analyses did not include reexamining the

allocation and flow of forces to the second MRC based on the different

separation time and covered only a 1997 scenario. Furthermore, these

analyses used different measures of effectiveness than the Nimble Dancer

baseline scenario. In commenting on a draft of this report, DOD noted that

the analyses provided insights concerning risk and other issues associated

with the different separation times.

Amount of Warning Time

Before the Attack

In Nimble Dancer, DOD used assumptions similar to the DPG about warning

times—the number of days warning before the enemy attacks. These

warning times are more favorable than those used by the combatant

commands, which estimate significantly different warning times.

According to the terms of reference, DOD considered performing sensitivity

analyses on warning times. Representatives from two combatant

commands—U.S. Central Command and U.S. Forces Korea—participating

in the game performed analyses that included different warning times than

the baseline scenario. According to command officials, these analyses

were conducted in a relatively short period of time and were not

structured or intended to comprehensively examine the warning time

issue. The scope of these analyses covered individual MRC scenarios in the

1997 time frame and did not address a two-MRC situation or the 2001-2005

time frame. Furthermore, the Central Command analysis used different

measures of effectiveness than DOD used in the Nimble Dancer baseline

scenario.

Page 7 GAO/NSIAD-96-170 Bottom-Up Review
B-272119 

Location of End States In Nimble Dancer, DOD assumed end states (the point where hostilities

cease in the MRCs) based on U.S. forces achieving certain objectives similar

to those in the DPG and used by combatant commands. However, the Joint

Staff and combatant commands differ on the geographic location where

these end state objectives would be achieved.

As part of the different warning analyses previously described, U.S. Forces

Korea and U.S. Central Command representatives participating in the

game examined the implications of achieving more aggressive end states

than used in the baseline scenario. According to command officials, their

review of the implications of using more aggressive end states was done

relatively quickly and was not structured or intended to be a

comprehensive assessment. The scope of their analyses addressed

individual MRC scenarios in 1997 and did not cover a two-MRC situation. The

analyses also did not address the 2001-2005 time frame.

DOD Did Not Fully

Analyze the Impact of

Some Critical Issues

During Nimble Dancer, DOD did not fully analyze certain issues that it

deemed critical to the success of fighting and winning two MRCs. For

example, DOD’s analyses on chemical warfare and the extraction of forces

from peace operations were limited in scope and did not fully assess the

impact of these issues on the MRCs. Furthermore, DOD’s analysis of other

critical issues, such as the sufficiency of support forces, effectiveness of

intelligence capabilities, and the use of the Army National Guard enhanced

brigades primarily consisted of discussions, and in some cases, DOD

deferred detailed analysis to other studies. Because of its limited analysis,

DOD lost opportunities to acquire additional information on the impact of

some critical issues on U.S. capabilities. DOD relied on military

judgment—an integral part of any war game—throughout Nimble Dancer.

In those cases where modeling and other analytical results were not

available, DOD based its conclusions exclusively on military judgment.

Chemical Warfare DOD identified chemical warfare as a critical issue, but it did not fully

examine the issue during Nimble Dancer. In the game’s 1997 baseline

modeling, the Joint Staff modeled only a limited amount of chemical

weapons. Because of the amount of chemical weapons used in the

baseline scenario, some Nimble Dancer participants did not believe the

scenario provided a realistic representation. DOD did not adjust the 1997

baseline to increase the volume of chemical attacks.

Page 8 GAO/NSIAD-96-170 Bottom-Up Review
B-272119 

During Nimble Dancer’s 2001 and 2005 assessments, DOD excluded

chemical weapons from the baseline modeling. Instead, DOD contracted

with BDM Federal, Inc., to conduct a separate analysis on the use of

chemical weapons in a specific individual MRC scenario. DOD officials said

that BDM had a proprietary model that was superior to DOD models for

simulating chemical warfare. BDM, as tasked by DOD, did not examine the

impact of chemical weapons on some key factors that could affect the

outcome of the conflict and did not perform sensitivity analyses on certain

key assumptions. The BDM analysis also did not use certain measures of

effectiveness established for Nimble Dancer. The Nimble Dancer terms of

reference and study plan identified the number of days to halt the enemy

advance, start the counterattack phase, and complete U.S. objectives as

measures of effectiveness. However, in accordance with DOD tasking, BDM

limited its analysis to the halt phase. Additionally, the final results of the

separate BDM analysis became available at the second phase of the

Nimble Dancer 2001-2005 war game. Thus, the results were unavailable to

earlier participants.

Extraction of Forces From

Peace Operations

In Nimble Dancer, DOD identified the extraction of forces from peace

operations as a critical issue, but its analysis of the issue has some

limitations. In the 1997 scenario, DOD officials told us they identified the

types of forces that might need to be extracted to fight the MRCs by taking

a “snapshot” of forces engaged in peace operations as of August 1994.

Although DOD identified potential shortages in certain types of units, they

did not examine the impact of those shortages. In addition, they did not

analyze any delays or lift requirements associated with extracting such

forces from the peace operations and transporting them to the MRCs.

DOD conducted a separate analysis to examine the issue of extracting

forces from a peace operation in the 2001-2005 time frame. Specifically,

DOD examined the impact of extracting 25,000 U.S. troops from Bosnia and

redeploying them to a MRC. DOD’s analysis, however, did not test the

sensitivity of its assumption that sufficient strategic lift would be available.

This is particularly critical because of the competing demands for lift

between the peace operation and both MRCs. Additionally, DOD did not

complete the separate analysis until the final phase of the war game. Thus,

the results were unavailable to participants in the first two phases of the

war game.

Sufficiency of Support

Forces

In Nimble Dancer, DOD identified the availability of sufficient support

forces as critical to the outcome of the conflict and determined that

Page 9 GAO/NSIAD-96-170 Bottom-Up Review
B-272119 

shortages could delay the start of the counterattack in the second MRC.

However, DOD did not model or analyze in detail the sufficiency of combat

support forces. For example, DOD did not examine actual requirements or

the readiness or adequacy of support forces to meet those requirements.

For the purpose of the baseline modeling, DOD assumed that support

forces would accompany combat units when they deployed. While game

participants acknowledged the shortages in support forces, the impact of

these shortages on the conflict was not analyzed. Treatment of these

issues was limited to identifying and discussing functional areas where

shortages were anticipated, such as seaport operations, trucking, heavy

construction engineering, and police work. DOD officials also discussed

alternative ways to resolve support shortages, including increased

allied/host nation support and use of contractor support.

In-depth analysis was deferred to an ongoing Army study—the Total Army

Analysis—a biennial process for determining support needs. This process

identifies the numbers and types of units needed to support combat units

in two MRCs and the personnel needed to fill these units. The Total Army

Analysis, completed in January 1996, concluded that about 60,000 required

positions are presently unfilled. DOD and the Army are continuing to

examine options for meeting support force requirements.

An example of a key combat support function for which DOD did not

perform any modeling or meaningful analysis involved the medical

treatment of casualties. In Nimble Dancer, DOD assumed that medical

support would be adequate to handle all U.S. casualties and postponed

further examination pending the outcome of the Total Army Analysis and

other ongoing studies within DOD, such as the update of the section 733

study.5

 Although the study plan specified casualty rates as one measure of

effectiveness, DOD did not analyze either U.S. or allied casualty rates in

Nimble Dancer. Casualties greatly affect support requirements and the

flow of forces into the theater. High casualty estimates translate into high

support requirements (for example, consumables such as water, blood,

and surgical supplies; lift assets for evacuating casualties out of theater;

and engineers to assemble hospital structures in-theater).

Effectiveness of

Intelligence Capabilities

Based on Nimble Dancer, DOD concluded that continued enhancements to

intelligence capabilities (such as increased timeliness and interoperability

and more systems such as the Joint Surveillance and Target Attack Radar

5

Section 733 of the National Defense Authorization Act for Fiscal Years 1992 and 1993 required DOD to

conduct a study to, among other things, determine the size and composition of the military medical

care system needed to support U.S. forces.

Page 10 GAO/NSIAD-96-170 Bottom-Up Review
B-272119 

System) were critical for U.S. forces to fight and win two MRCs. These

enhancements are closely linked to precision-guided munitions because

improved intelligence capabilities are required for effective targeting of

these weapons.6

 The services project that inventories of these

precision-guided munitions will increase dramatically between the 1997

and 2001-2005 time frames.

While DOD originally considered performing some sensitivity analyses

during Nimble Dancer, it did not model or otherwise conduct in-depth

analyses on intelligence capabilities. DOD officials said existing models

were inadequate for such analyses and that they reached conclusions

about intelligence by reviewing the earlier Intelligence Bottom-Up Review

and applying the military judgment of Nimble Dancer participants. Some

participants, including flag officers, were concerned about reaching such

conclusions without detailed supporting analyses. DOD officials said that

because they could not model certain intelligence capabilities, they

deferred more in-depth analysis to a subsequent war game (known as

Nimble Vision), which they plan to complete in the summer of 1996.

Army National Guard

Enhanced Combat

Brigades

According to the Bottom-Up Review, 15 Army National Guard enhanced

brigades are part of the Army’s force structure needed to fulfill the

two-MRC requirement. In Nimble Dancer, DOD identified these brigades as

available to respond during two MRCs. These brigades were also included

in the list of force enhancements that DOD deemed critical to the U.S.

success in fighting and winning two MRCs. During Nimble Dancer, DOD

officials discussed the brigades in seminar discussions. However, they did

not perform any detailed analysis on how deploying the brigades would

affect U.S. capability. Although DOD’s baseline modeling of combat

scenarios for 1997, 2001, and 2005 assumed that 15 brigades would be

mobilized early in the first MRC and that 5 of the brigades would be ready

to deploy within 90 days, none of the brigades actually deployed. They

were, therefore, not part of the forces used in either MRC.

According to DOD officials, Nimble Dancer did not conduct detailed

analyses on enhanced brigades because the scenarios in the modeling did

not involve adverse conditions, including the need for additional capability

to counter high-intensity chemical attacks or to prosecute a more

aggressive end state. Therefore, they assumed that 10 active Army

divisions provided sufficient combat capability. During senior-level

6

Precision-guided munitions include the Army Tactical Missile System with the Brilliant Anti-Armor

Submunition, Longbow Hellfire missile, Sensor Fused Weapon, Joint Direct Attack Munition, and Joint

Standoff Weapon.

Page 11 GAO/NSIAD-96-170 Bottom-Up Review
B-272119 

seminar discussions, Army and combatant command officials emphasized

that enhanced brigades would be needed in two MRCs; however, opinions

varied as to the number and type of brigades required and the capability of

the brigades to meet the Bottom-Up Review’s goal of being ready to deploy

90 days after call-up.

DOD Relied Heavily and

Sometimes Exclusively on

Military Judgment During

Nimble Dancer

DOD relied heavily on the military judgment of seminar participants

throughout Nimble Dancer. DOD officials told us that in reaching the

overall conclusion that the war game tested and validated Bottom-Up

Review assumptions and showed that U.S. forces can fight and win two

MRCs, participants applied their judgment based on extensive military

experience when assessing the implications of modeling and other

analytical results. The use of military judgment in providing input to the

war game models and in analyzing the output is a necessary part of any

war game because models by themselves are not predictive.

In some cases where analytical results were not available, military

judgment was the sole basis for reaching conclusions. For example, DOD

officials told us that because current models used by the Joint Staff cannot

simulate the impact of specific force enhancements, such as

precision-guided munitions and upgrades in intelligence capabilities, they

judged—based on their collective experience—these enhancements to be

critical to the success of U.S. forces to respond to two MRCs. Also, as

previously discussed, DOD deferred analyses of certain critical issues, such

as sufficiency of support forces and intelligence capabilities. In these

cases, Nimble Dancer participants relied solely on their military judgment

to determine that potential vulnerabilities associated with these issues

would not preclude U.S. forces from fighting and winning two MRCs. In

commenting on a draft of our report, DOD stated that in assessing issues

where modeling support is not sufficiently mature or timely, it is common

to rely on the combined judgment of senior players to arrive at a

conclusion.

Agency Comments

and Our Evaluation

DOD provided written classified comments on the classified version of this

report. We summarized their comments below. We also incorporated their

comments in the report where appropriate.

DOD disagreed with our finding that key assumptions used in Nimble

Dancer were generally favorable and that DOD generally did not perform

sensitivity analyses to test the impact of using more adverse assumptions.

Page 12 GAO/NSIAD-96-170 Bottom-Up Review
B-272119 

DOD stated that it based game scenarios and assumptions on the May 1994

DPG to provide a common reference point for game participants. DOD noted

that it conducted considerable analyses and war game discussions on the

assumptions to assess their impact on U.S. ability to fight and win two

MRCs. These analyses and discussions, according to DOD, provided various

insights, including potential risks associated with more adverse

assumptions and the importance of timely national decision-making, and

helped support recommendations for continuing programmed force

enhancements. In its comments, DOD summarized the extent of analysis

conducted on certain game assumptions.

We recognize that Nimble Dancer involved analyses and discussions of key

assumptions, enabling game participants to gain insight into various

aspects of the two-MRC requirement. Based on additional information

provided by DOD, we modified the text to reflect the extent of DOD’s

analyses on the sensitivity of certain assumptions and our assessment of

these analyses. We continue to believe that certain game assumptions

were favorable because they set conditions that were mostly advantageous

to U.S. forces, thereby minimizing risk. Based on DOD’s public comments

that the game involved rigorous and robust analyses, we expected that DOD

performed considerable and varied sensitivity analyses to test the

sensitivity of scenario assumptions. We agree that DOD examined the

impact of adverse circumstances for some assumptions. However, we

found that in some cases the scope of analysis was limited, such as

focusing on individual MRCs rather than a two-MRC situation or covering

only part of the Nimble Dancer time frame.

DOD partially concurred with our finding that certain critical issues were

not fully examined. DOD acknowledged that some issues were not analyzed

exhaustively and were deferred to follow-on studies; however, it noted

that considerable analysis was conducted during Nimble Dancer. DOD also

stated that its leadership recognized that there would be practical limits to

the scope of analysis within the time frames and resources available and

fully considered these limitations in constructing and executing Nimble

Dancer. Based on DOD’s comments, we modified the text to clarify the

extent of analysis provided on critical issues and our evaluation of this

analysis. We continue to believe that Nimble Dancer did not fully examine

certain critical issues to the level implied in DOD’s public comments that

the game involved rigorous and robust analyses.

DOD also believed that we implied that the game relied too heavily on

military judgment. We do not believe that the report gives this impression.

Page 13 GAO/NSIAD-96-170 Bottom-Up Review
B-272119 

Rather, as reflected in the text, we recognize the role and value of military

judgment in a game like Nimble Dancer. We did not reach a conclusion

about the appropriateness of DOD’s application of military judgment.

Rather, we describe the circumstances in which such judgment was

applied, including those instances where it was the sole basis for reaching

conclusions.

Scope and

Methodology

To review the methodology, assumptions, and results of Nimble Dancer,

we interviewed knowledgeable officials at the Office of the Secretary of

Defense; the Joint Chiefs of Staff; the Defense Intelligence Agency; the

Central Intelligence Agency; the Army, the Air Force, the Navy, and the

Marine Corps headquarters; and two defense contractors—BDM Federal,

Inc., and the Johns Hopkins University Applied Physics Laboratory. Our

scope was limited to reviewing the Nimble Dancer war game. We did not

attempt to independently assess the ability of U.S. forces to meet the

Bottom-Up Review’s two-MRC requirement.

We also interviewed or obtained written responses from officials at the

U.S. Central Command, the U.S. Pacific Command, and U.S. Forces Korea

to obtain information on their participation in Nimble Dancer and their

views on its methodology, assumptions, and results.

We reviewed relevant documentation, including briefing slides and

information papers prepared for Nimble Dancer discussion seminars, DOD

and contractor analyses of selected two-MRC issues, and other pertinent

documentation. DOD officials denied us access to specific supporting

documentation on DOD’s baseline modeling, and we therefore could not

verify the specific nature and results of the modeling effort. DOD did not

write an after-action report on Nimble Dancer to summarize its analyses or

conclusions. Accordingly, we reviewed briefing slides summarizing the

modeling effort. However, these slides lacked specific details such as

information about the types and quantities of force enhancements used for

the 2005 scenario.

We performed our review between August 1995 and March 1996 in

accordance with generally accepted government auditing standards.

We are providing copies of this report to the Chairmen and Ranking

Minority Members, Senate Committee on Armed Services, the

Subcommittee on Defense, Senate Committee on Appropriations, and the

Page 14 GAO/NSIAD-96-170 Bottom-Up Review
B-272119 

Subcommittee on National Security, House Committee on Appropriations;

the Secretaries of Defense, the Air Force, the Army, and the Navy; the

Commandant of the Marine Corps; and the Director, Office of Management

and Budget. We will also make copies available to others upon request.

If you have any questions concerning this report, please call me on

(202) 512-3504. Major contributors to this report were Sharon Pickup,

Stephen L. Caldwell, Marc Schwartz, and Vincent Truett.

Richard Davis

Director, National Security

 Analysis

Page 15 GAO/NSIAD-96-170 Bottom-Up Review
Appendix I 

GAO Responses to Specific Questions From

the House National Security Committee

In the letter requesting our review, the Committee asked 15 specific

questions. Table I.1 provides information on those questions that we were

able to address in an unclassified manner. The format of the questions has

been changed to better match the table below.

Table I.1: Information on Selected Nimble Dancer Assumptions and Analyses

Committee question Nimble Dancer assumption/process Comments on analysis/use of data

What assumptions were

made about readiness?

Assumed all U.S. active and reserve forces were

100 percent ready upon deployment (i.e.,

manned, trained, and equipped).

Assumption appears favorable. Sensitivity

analysis was considered by the Joint Staff but

was not done.

What assumptions were

made about deployability?

Assumed all units deployed as scheduled with no

delays at ports or airfields.

Assumption appears favorable. Sensitivity

analysis was considered by the Joint Staff, but

was not done.

What assumptions were

made about force

modernization?

In 1997 and 2001 scenarios, DOD assumed

Bottom-Up Review force enhancements would be

available as scheduled and in quantities

programmed in 1996-2001 Future Years Defense

Program. In 2005 scenario, assumed quantities

as projected by military services.

Availability of force enhancements identified as a

critical issue. Assumptions appear favorable. No

sensitivity analysis done to examine impact if

program schedule delays occur. Modeling

adjusted to reflect quantities in 1997, 2001, and

2005. Modeling results reflect aggregate

contributions of precision-guided munitions and

accelerated force flow due to additional

prepositioning and lift. Model unable to isolate

impact of individual force enhancements. We

were unable to verify enhancement types and

quantities because DOD officials denied us data.

What assumptions were

made about the level of

acceptable casualties?

Casualty rates were not analyzed. DOD originally identified casualties as a measure

of effectiveness but decided not to use this

measure.

What assumptions were

made about the enemy’s

use of weapons of mass

destruction?

Baseline modeling included limited use of

chemical weapons.

Mitigating the impact of chemical and biological

warfare identified as a critical issue. Use of

chemicals in baseline scenario for certain time

frame considered unrealistic by some

participants due to amount of chemicals used. No

adjustments made to change amount. Baseline

assumptions for another time frame were

favorable because no chemicals were used. A

separate analysis done by BDM Federal, Inc.,

had some limitations: used some favorable

assumptions, did not examine certain factors,

and used different measures of effectiveness

than baseline.

What assumptions were

made about the readiness

of U.S./allied forces to

operate in a nuclear,

biological, or chemical

environment?

When chemical weapons were factored into

scenario (i.e., 1997 baseline scenario and 2005

BDM analysis) DOD and BDM analyses assumed

U.S. forces were prepared to operate in a

contaminated environment. Allied nuclear,

biological, and chemical readiness not

addressed.

Mitigating the impact of chemical and biological

warfare identified as a critical issue. Assumption

appears favorable. No sensitivity analysis done.

(continued)

Page 16 GAO/NSIAD-96-170 Bottom-Up Review
Appendix I 

GAO Responses to Specific Questions From

the House National Security Committee

Committee question Nimble Dancer assumption/process Comments on analysis/use of data

What assumptions were

made about forces

participating in the two

MRCs?

Assumed Bottom-Up Review force structure

would be in place for 1997 and 2001-2005

scenarios. Assumed entire force would

participate in the MRCs, except for the 15

National Guard enhanced brigades because

circumstances not considered adverse enough

for their use.

Force participation consistent with the DPG.

Combatant commands describe importance of

enhanced brigades as a strategic reserve force.

Modeling was not adjusted to account for

redeployment of forces from peace operations.

(See separate entry on peace operations.)

What assumptions were

made about defense

budgets?

Used the 1996-2001 Future Years Defense

Program for 1997 and 2001 scenarios. DOD

stated service projections were used for the 2005

scenario.

No sensitivity analysis done to test impact if

enhancements not available as planned. DOD

officials denied us access to 2005 weapon

system and weapon quantities.

What assumptions were

made about mobilization?

Assumed rapid decision-making by national

command authorities.

Timeliness of national decision-making identified

as important. Assumptions are the same as DPG

and appear favorable. Sensitivity analysis was

considered by the Joint Staff, but was not done.

What assumptions were

made about activation of

the Civil Reserve Air Fleet?

Assumed rapid activation by national command

authorities.

Timeliness of national decision-making identified

as a critical issue. Assumptions are the same as

DPG and appear favorable. Sensitivity analysis

was considered by the Joint Staff but was not

done.

What assumptions were

made about access to

overseas bases?

Assumed there would be no access problems. Assumptions appear favorable. No sensitivity

analysis done.

What assumptions were

made about U.S. nuclear

retaliation?

No use of nuclear weapons by U.S. or enemy

forces.

What were the Nimble

Dancer war game

objectives?

Objectives were to assess ability of programmed

U.S. forces to fight and win two nearly

simultaneous MRCs in 1997 and 2001-2005 time

frames and to identify critical issues related to the

two-MRC requirement.

DOD used measures of effectiveness (risk;

forward line of troops; and days to complete halt,

buildup, and counterattack) in modeling results.

DOD relied on military judgment throughout

game. DOD concluded U.S. forces could fight

and win two MRCs in 1997 and 2001-2005 time

frames, stating that Nimble Dancer tested and

validated basic Bottom-Up Review assumptions.

DOD emphasized importance of continuing force

enhancements and timely decision-making.

What assumptions were

made about the war

termination conditions?

End state conditions required U.S. forces to

achieve certain objectives.

End state conditions consistent with DPG. U.S.

Central Command and U.S. Forces Korea did

analyses using alternative end states. Per

command officials, analyses were done quickly

and not structured or intended to be

comprehensive. Scope limited to individual MRCs

in 1997 and did not address a two-MRC situation

or 2001-2005 time frame.

What models were used? Game used more than 15 models. Key model to

simulate war was TACWAR. Other models

included FDE and MIDAS (for deployment), ITEM

(maritime and air battle), THUNDER (air battle),

and METRIC (chemical warfare).

(continued)

Page 17 GAO/NSIAD-96-170 Bottom-Up Review
Appendix I 

GAO Responses to Specific Questions From

the House National Security Committee

Committee question Nimble Dancer assumption/process Comments on analysis/use of data

What were the models’

strengths and limitations?

TACWAR models ground battle at operational

level but cannot model intelligence capabilities,

combat support forces, or maneuver warfare.

FDE and MIDAS model intertheater force flow but

cannot model intratheater transport. ITEM (Navy)

models naval warfare and airpower but cannot

model the ground battle. THUNDER (Air Force)

models airpower and the ground battle but

cannot model naval surface warfare or

amphibious operations.

No single model can simulate everything. DOD

recognizes limitations and has a joint model

improvement program underway.

Was the seminar war

game format sufficient to

provide a definitive

assessment that the

two-MRC requirement is

supportable?

Models alone are not predictive or conclusive.

Seminar provided forum for discussing model

results and critical issues.

Seminar results were not documented in an

after-action report. No format can provide a

definitive assessment—only fighting the war can.

Beyond the baseline

modeling, were any

sensitivity analyses or

separate analyses done?

Complete sensitivity analyses done on sequence

of MRCs. Limited sensitivity analyses on strategic

warning, separation time between the MRCs, and

war termination conditions (end states). Separate

analyses done on chemical warfare and

extracting forces from peace operations.

DOD officials originally considered conducting

several sensitivity analyses, but some were not

done, and others had limited scope, making

comparisons with the baseline difficult. (See

separate entries on mobilization, Civil Reserve Air

Fleet, strategic warning, separation time between

the MRCs, war termination conditions, enemy use

of weapons of mass destruction, and peace

operations.)

What assumptions were

made about strategic

warning?

Assumed unambiguous warning times similar to

those used in the DPG.

U.S. Central Command and U.S. Forces Korea

did analyses using different warning times. Per

command officials, analyses were done quickly

and not structured or intended to be

comprehensive. Scope was limited—only

addressed individual MRCs in 1997. Central

Command’s analysis used different measures of

effectiveness than the baseline.

What assumptions were

made about separation

time between the MRCs?

Assumed a separation time between the two

MRCs that was consistent with the DPG.

Assumption is consistent with the DPG and

appears favorable. U.S. Central Command and

DOD’s Program Analysis and Evaluation office

did analyses using different separation times. Per

command and DOD officials, analyses were done

relatively quickly and not structured or intended

to be comprehensive. Scope of analysis was

limited—addressed 1997 only, did not reallocate

force flows, and used different measures of

effectiveness than the baseline.

What assumptions were

made about U.S.

response to strategic

warning?

Assumed a series of flexible deterrent options. Assumptions used in war fighting and

deployment models. Flexible deterrent options in

2001-2005 scenario were exercised earlier and

were more aggressive than in 1997 scenario.

(continued)

Page 18 GAO/NSIAD-96-170 Bottom-Up Review
Appendix I 

GAO Responses to Specific Questions From

the House National Security Committee

Committee question Nimble Dancer assumption/process Comments on analysis/use of data

What assumptions were

made about the

availability and

deployability of support

forces?

Baseline modeling assumed support forces

(combat support and combat service support)

were sufficient to support combat forces.

Sufficiency of support forces identified as a

critical issue. War modeling implicitly assumes

support forces available. Identified possible

shortages of types of units (e.g., engineers, port

handlers, military police, transport). In-depth

analysis deferred to Total Army Analysis 2003.

What assumptions were

made about the

availability and

deployability of forces

engaged in peace

operations?

Baseline 1997 and 2001-2005 scenarios

assumed that peace operation forces would be

extracted and redeployed to support MRCs when

needed. The 1997 scenario used a “snapshot” in

time (Aug. 18, 1994) to identify forces that might

be needed in the MRCs but did not model the

impact of extracting these forces.

Impact of extracting forces from peace

operations identified as a critical issue. Baseline

assumptions appear favorable. Separate analysis

done on impact of extracting and redeploying

25,000 forces from Bosnia peace operation to an

MRC in the 2001-2005 time frame. No sensitivity

analysis done on sufficiency of lift, nor was the

impact on peace operations examined.

What factors could have

affected the outcome of

Nimble Dancer?

Change in key assumptions (e.g., separation and

warning times, timing of decision-making, enemy

capabilities, and access to ports and bases)

could affect risk, location of end states, and

length of each MRC.

Limited sensitivity analysis done on key

assumptions.

How were assumptions

set?

Assumptions based primarily on existing

guidance and studies (DPG, Mobility

Requirements Study Bottom-Up Review Update,

Defense Intelligence Agency data).

Assumptions appear generally favorable.

How were disagreements

resolved?

Participants disagreed on some key issues. When applicable, disagreements were resolved

by using assumptions in the DPG. For issues not

addressed by the DPG, the Joint Staff made the

final decision after participants discussed the

issues.

What assumptions were

made about access to

ports and bases and host

nation support?

Assumed there would be no access problems. No sensitivity analysis done. Assumptions used in

war modeling.

(701082)(701092) Page 19 GAO/NSIAD-96-170 Bottom-Up Review
Ordering Information

The first copy of each GAO report and testimony is free.

Additional copies are $2 each. Orders should be sent to the

following address, accompanied by a check or money order

made out to the Superintendent of Documents, when

necessary. VISA and MasterCard credit cards are accepted, also.

Orders for 100 or more copies to be mailed to a single address

are discounted 25 percent.

Orders by mail:

U.S. General Accounting Office

P.O. Box 6015

Gaithersburg, MD 20884-6015

or visit:

Room 1100

700 4th St. NW (corner of 4th and G Sts. NW)

U.S. General Accounting Office

Washington, DC

Orders may also be placed by calling (202) 512-6000 

or by using fax number (301) 258-4066, or TDD (301) 413-0006.

Each day, GAO issues a list of newly available reports and

testimony. To receive facsimile copies of the daily list or any

list from the past 30 days, please call (202) 512-6000 using a

touchtone phone. A recorded menu will provide information on

how to obtain these lists.

For information on how to access GAO reports on the INTERNET,

send an e-mail message with "info" in the body to:

info@www.gao.gov

or visit GAO’s World Wide Web Home Page at:

http://www.gao.gov

PRINTED ON RECYCLED PAPER
United States

General Accounting Office

Washington, D.C. 20548-0001

Official Business

Penalty for Private Use $300

Address Correction Requested

Bulk Rate

Postage & Fees Paid

GAO

Permit No. G100