Structuring the Active and Reserve Army for the 21st Century
December 1997
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Chapter Two

The Army's Force Requirements for Various Missions

The U.S. Army is one of the largest in the world.(1) Its size reflects the significant military capability that the Army must provide to support the Administration's national security strategy. As outlined in Chapter 1, that strategy includes various military missions, such as fighting two nearly simultaneous major regional conflicts (MRCs), conducting peacekeeping operations and providing humanitarian assistance, and maintaining a U.S. presence overseas.

In determining the size of the forces to carry out those missions, the Administration has concluded that the United States must field enough troops to fight and win two major regional conflicts, each similar in size to the Persian Gulf War, that occur at roughly the same time. (In the Administration's view, if the military did not have enough forces to deal with a second conflict, other nations would be more likely to try to take advantage of the United States while it was involved elsewhere.) Forces that are large enough to fight two nearly simultaneous MRCs should be more than sufficient to carry out the less demanding missions of peacekeeping and overseas presence, although perhaps not all at the same time.

What foes should the United States be prepared to fight in the near future? The Department of Defense's (DoD's) Quadrennial Defense Review identified several regional dangers that DoD believes will confront the nation between now and 2015. First among those is the threat that Iran and Iraq pose to the free flow of Middle Eastern oil. Next is the threat that North Korea presents to South Korea because of its increasingly dire economic condition and its large military presence close to the South Korean border.

In line with those threats, the forces of Iran, Iraq, and North Korea form the backdrop for DoD's current planning. Much of that planning is based on the ability to provide enough military force to fight conflicts that break out on the Korean Peninsula and in the Persian Gulf region nearly simultaneously. Former Defense Secretary Les Aspin, in his Report on the Bottom-Up Review, postulated that the Army would need to provide four to five divisions of combat forces for each of those conflicts. Some defense analysts have questioned the validity of that requirement and of the two-conflict scenario as a whole (see Box 1). Nevertheless, current Defense Secretary William Cohen has reaffirmed Aspin's requirement, at least for the near future.

Box 1.
How Realistic Are the Two-MRC Requirements?

Not all defense analysts believe that the U.S. Army must be prepared to fight two major regional conflicts (MRCs) similar to Operation Desert Storm at the same time. According to Michael O'Hanlon of the Brookings Institution, although the Administration's policy is to be able "to fight and win two major regional wars at once, the nation has probably never had that capability since World War II, and it is hard to see why we should start now."1

Even when analysts concede the validity of the two-MRC scenario, some argue that the Department of Defense (DoD) is overstating the number of U.S. forces needed to fight those wars. Both O'Hanlon and Lawrence Korb, a former DoD official who is now also at the Brookings Institution, contend that smaller forces than those planned by the Pentagon would be more than adequate to fight wars in Korea and the Persian Gulf (the major regions of concern highlighted in the Quadrennial Defense Review). According to Korb, the U.S. intelligence community has concluded that South Korea is capable of defending itself from North Korea without help from U.S. forces. Korb also asserts that the Iraqi military is now less than half as powerful as it was during Operation Desert Storm. As a result, he concludes that the U.S. military is already more than capable of fighting two nearly simultaneous Desert Storms.2

Carrying the argument further, O'Hanlon postulates that the United States could carry out its two-MRC strategy with fewer combat forces than it has today. That conclusion is based on two arguments. First, he maintains that the Pentagon is too pessimistic about the likely requirements for waging wars in Korea and the Persian Gulf region. As a result, smaller ground forces than those called for in U.S. military planning would be adequate to fight wars there. Second, O'Hanlon asserts that the chance of such large U.S. forces being needed in two places at once is remote. Instead, he argues that a small U.S. ground force could hold the enemy at bay in a second theater while U.S. air forces inflicted heavy damage. That approach would require fewer ground forces, in total, than the Administration plans to keep in the U.S. military. Those two arguments lead O'Hanlon to conclude that the Army and Marine Corps could safely reduce their forces by about 10 percent.3

1. Michael E. O'Hanlon, "The New Order: Pentagon Lite," Los Angeles Times, December 9, 1996, p. B5.

2. Lawrence J. Korb, "More Than Ready for Two Desert Storms," Washington Post, January 29, 1997, p. A21.

3. Michael E. O'Hanlon, The Pentagon's Quadrennial Defense Review, Policy Brief No. 15 (Washington, D.C.: Brookings Institution, April 1997).


Force Requirements for Two Major Regional Conflicts

Fighting two MRCs at the same time would, according to the Army, require nearly all of the deployable forces in the active component and most of those in the reserves. However, the Army says it lacks enough deployable support forces to conduct two major wars simultaneously with sufficiently low risk. At the same time, the Army has combat forces in the reserves that would not take part directly in either of two MRCs as those conflicts are now envisioned.

Determining Force Requirements

The Army relies on an analytic process to determine its total force needs. Using a method called the Total Army Analysis (TAA), the Army reviews its force-structure requirements every two years. The TAA method begins with the number of combat forces that DoD has decided will provide the military capability necessary to carry out U.S. national security strategy. For each major regional conflict, the Army assumes that it would need to provide a minimum of 5 1/3 divisions. Thus, to fight two MRCs, the Army would need to deploy at least 10 2/3 divisions--or 32 out of the 33 combat brigades in the active Army.

Based on the number of combat forces, the TAA process determines how many and what kind of support forces are necessary to accompany those combat units overseas. Specifically, the analysis estimates how many people the Army needs in combat-support and combat-service-support units besides those belonging to combat divisions and brigades. Combat-support forces provide operational support, such as air defense and combat engineering, for combat forces. Combat-service-support units typically perform personnel, medical, logistics, or administrative functions. The support requirements in the Total Army Analysis also include people whom the Army must dedicate to support other services, primarily in transportation and quartermaster units (they represent about 6 percent of total support requirements).

The results of the Total Army Analysis released in January 1996--the most recent that are publicly available--reflect work that was completed in the summer of 1995. Because it was designed to determine the shape of the Army in 2003, that analysis is known as the Total Army Analysis 2003 (TAA-03).

The TAA-03 yielded a requirement for 672,000 deployable troops to fight two nearly simultaneous major conflicts. Of those, 195,000 would be combat troops. The other 477,000 (over 70 percent) would be support forces, which would outnumber combat troops by almost 2.5 to 1. That requirement is not without controversy, however, because it differs from both previous analytic results and actual combat experience.

Differences with Other DoD Studies. The Total Army Analysis 2003 yielded a force requirement for two regional conflicts that is significantly higher than those associated with other DoD studies. Shortly before the TAA-03, DoD analyzed the military's need for transport ships and aircraft. That analysis, called the Mobility Requirements Study Bottom-Up Review Update, was based on an assumed need to deliver 457,000 Army troops and their equipment to fight two MRCs--far fewer than the 672,000 troops that the Army says would be necessary.(2)

Part of the difference between the forces assumed to be deployed in the Mobility Requirements Study and the Total Army Analysis 2003 is that the latter includes six National Guard combat brigades that the Army would send to the second MRC to reinforce the 5 1/3 active divisions. Those reinforcing units account for an additional 30,000 combat troops.

The other 185,000-person difference between the number of Army forces deployed in the two studies comes in the area of support troops. A few of the additional support troops in the TAA-03 (about 10,000) are associated with the six Guard combat brigades that the Army includes in its analysis. Another 30,000 or so are associated with a second corps command structure that the Army believes it would need in Korea. A corps typically has two to five divisions under its command, and one Army corps organization is permanently stationed in South Korea. Nevertheless, the Army assumed in the TAA-03 that it would deploy another corps organization from the United States to help control operations in the event of a conflict in Korea. Since adequate command structure already appears to be in place in Korea for the 5 1/3 divisions that would fight there, some people have questioned the need for the 30,000 extra support personnel.

Two other factors contributed to the large requirement for support troops in the Total Army Analysis 2003. First, the study assumed that citizens of the countries where the conflicts were being fought would provide very little logistical support. Previous analyses, including the Mobility Requirements Study, assumed that the host nations involved in the two wars would provide greater levels of support--as much as the equivalent of 42,000 support soldiers in all, including fuel-supply and transportation workers. (During the Persian Gulf War, for example, Saudi Arabia provided trucks and drivers, thus reducing the number of troops and the amount of equipment that the U.S. Army had to transport to the region.) The Total Army Analysis 2003, however, assumed a much lower contribution from the host nations, which boosted its requirement for support troops by 28,000.

Second, the Army's analysis projected historically high rates of fuel consumption and medical casualties. One study performed for the Office of the Secretary of Defense contends that the force requirements in the TAA-03 are based in part on assuming that rates of activity that represent historical peaks are sustained for long periods of time.(3) Those assumptions in turn lead to large demands for fuel and generate large numbers of casualties. The number of support personnel (truck drivers, fuel pumpers, nurses, and doctors) needed as a result is 68,000 higher than DoD assumed in its mobility analysis.

To some extent, the discrepancy between the numbers of Army troops sent to two MRCs in DoD's mobility study and the Total Army Analysis may result from the different purposes of the two studies. The Mobility Requirements Study was conducted to determine how many transport planes and ships (so-called airlift and sealift) the United States would need in order to move military forces overseas to fight two major regional conflicts. One of the constraints on that analysis was that the resulting lift fleet would have to be affordable under planned DoD budgets. As a consequence, the study's authors may have limited the number and types of forces deployed by the Army to those that an affordable lift fleet could move within a reasonable amount of time and with an acceptable level of risk.

By contrast, the TAA process for determining force requirements yields the number of forces that would be needed to minimize the Army's risk in fighting two MRCs. Furthermore, that process does not explicitly consider the mobility assets or time needed to move its resultant force--that is, it assumes a limitless availability of airlift and sealift.

Given the different approaches of the two studies, therefore, it is not surprising that they produce different results about how many Army forces would take part in two overlapping MRCs. Because the Mobility Requirements Study took into account the problems associated with moving a large military force overseas, its results are perhaps more representative of how the United States would actually conduct two nearly simultaneous wars.

Differences with Military History. The force requirements resulting from the TAA-03, particularly for support personnel, are much larger than historical evidence would suggest. In fact, the ratio of support to combat forces in the Total Army Analysis 2003 is around 40 percent to 80 percent higher than the ratios from past U.S. conflicts (see Table 3). That difference comes partly from the Army's desire to provide all of the support that its combat units could possibly need using its own forces, and partly from the questionable assumptions detailed above.

Table 3.
Ratio of Support Personnel to Combat Personnel in Defense Analyses and Actual Conflicts
Conflict or Analysis Ratio
(Support personnel to combat personnel)

World War II 1.7 to 1
Korean War 1.5 to 1
Vietnam War 1.8 to 1
Persian Gulf Wara 1.4 to 1
Mobility Requirements Study Bottom-Up Review Update 1.8 to 1
Total Army Analysis 2003 2.5 to 1

SOURCE: Congressional Budget Office based on John C.F. Tillson and others, Review of the Army Process for Determining Force Structure Requirements (Alexandria, Va.: Institute for Defense Analyses, May 1996); and Department of Defense, Military Traffic Management Command, Deployment Planning Guide (September 1994).
a. Just before the start of the ground war.

Two historical conflicts that exhibited low support-to-combat ratios--the Korean and Persian Gulf Wars--were ones in which the host nation contributed significantly to the war effort. During the Korean War, the Army relied on the services of 150,000 Koreans and an equal number of Japanese employees in Japan in addition to numerous contractors. During the Gulf War, the Saudi government provided or paid for more than 4,000 trucks, 1.5 million gallons per day of petroleum products, and over $2 billion worth of food. By contrast, the TAA-03 assumed very little in the way of host-nation support.

Even excluding the extraordinary contributions during the Korean and Persian Gulf Wars, the support requirements derived from the Army's analysis are high. They exceed those of such extended conflicts as World War II and the Vietnam War by about 40 percent. The support-to-combat ratio in those two conflicts was approximately the same one used for DoD's recent study of mobility requirements; the department labeled that ratio as representing a moderate risk. The current Army leadership may feel that additional support personnel will help reduce the risk in future conflicts below even a moderate level.

Although the results of the Total Army Analysis 2003 are not universally accepted, they form the basis for the Army's planning process and provide the service's most recent publicly available estimate of its requirements for deployable forces.(4) Despite objections by some people in the Office of the Secretary of Defense to the assumptions, DoD's civilian leadership ultimately approved changes to the Army's force structure based on the results of the analysis.

Forces Available to Fight Two MRCs

Overall, the Army has more deployable forces than the Total Army Analysis 2003 calls for, but those forces are not necessarily configured properly. The Army contains almost 780,000 soldiers in deployable units (40 percent in the active component and the rest in the reserves). That total exceeds the number of deployable soldiers required for two major regional conflicts by more than 100,000 (see Figure 2). However, an imbalance exists between the required mix of combat and support forces and the mix currently in the Army. The Army's analysis calls for 195,000 combat troops and 477,000 support troops to participate in two MRCs. But the Army planned for 1998 will contain 351,000 combat troops and less than 430,000 support troops. (Those numbers do not include the cuts recommended by the Quadrennial Defense Review.) In other words, the service will face a shortfall of at least 47,000 support forces compared with what the TAA process determined was necessary to fight two regional wars. In fact, when the analysis looked at the specific units required to support those wars, it yielded a larger shortage of support forces. It found that the Army needs more than 58,000 additional support personnel, with the largest needs in truck companies and units that handle fuel supplies.

Figure 2.
Number of Deployable Army Forces Compared with Requirements for two Major Regional Conflicts

SOURCE: Congressional Budget Office based on Ronald E. Sortor, Army Active/Reserve Mix: Force Planning for Major Regional Contingencies (Santa Monica, Calif.: RAND, 1995); and General Accounting Office, Force Structure: Army Support Forces Can Meet Two-Conflict Strategy with Some Risks, GAO/NSIAD-97-66 (February 1997).
NOTE: Requirements are based on the results of the Total Army Analysis 2003.

At the same time, according to the Army's own analysis, the service has an excess of combat forces. About half of its combat troops are in the active component. Because they are composed of full-time soldiers, active-duty combat units are the most prepared to fight in conflicts that erupt with little warning. For that reason, Army planning assumes that the first 10 2/3 combat divisions (165,000 out of the total 195,000 combat troops) deployed for two MRCs would come from the active Army. The remaining 30,000 combat troops would come from the National Guard. That leaves 145,000 combat forces in the Guard with no specific role to play in fighting two MRCs, according to the Total Army Analysis 2003 (see Figure 2).

In contrast to combat forces, most of the support forces used in the two major conflicts would come from the reserve component. Of the Army's total support forces, only 136,000 (less than one-third) are assigned to the active Army. The Army would need at least 217,000 support troops for a conflict on the Korean Peninsula, and even more--at least 250,000--for a war in the Persian Gulf region, where the Army does not have an extensive military presence and support structure.

Assembling so many support forces would require the Army to mobilize large numbers of reservists. That need was demonstrated during the Persian Gulf War. In January and February 1991, when the active Army contained around 750,000 troops, about 300,000 soldiers participated directly in the war. Nevertheless, more than 70,000 of the soldiers sent to the Persian Gulf were reservists, all assigned to support units.

The Army takes somewhat contradictory approaches to providing combat forces and support forces for its most demanding mission. In planning how to fight two MRCs, the Army relies almost exclusively on its active component for combat forces but leans very heavily on the reserves for support forces. The Army justifies that stance by arguing that it takes much less time to prepare reserve support units for deployment than reserve combat units. But at the same time, the Army's overall structure contains excess combat forces and (according to its analysis) insufficient support forces.

Force Requirements for Lesser Contingencies

The Army must also shape its forces to perform a host of less demanding but more likely missions--such as humanitarian assistance, peace enforcement, and smaller-scale combat operations. The Bottom-Up Review concluded that in planning for those types of missions, prudence would dictate using up to three Army divisions and a total of 50,000 combat and support personnel from all of the services.(5) It also declared that the forces slated to take part in peacekeeping or other humanitarian missions could be part of the same collection of forces needed for major regional conflicts.(6) That policy means that the United States would not be able to carry out sizable peace-enforcement or other operations at the same time that it was fighting two MRCs. But it also means that if the United States had sufficient forces to conduct two regional conflicts, it would have more than enough for those lesser contingencies.

During the past decade, the nation has been involved in several operations of much smaller scale than the Persian Gulf War. The United States intervened unilaterally in Panama in 1989 and in Haiti in 1994, each time with about 18,000 soldiers. A force that at one point included more than 19,000 U.S. soldiers is taking part in international peacekeeping efforts in Bosnia. By contrast, 16 times as many troops (about 300,000) were in the Middle East during the peak of the Gulf War. On a similar scale, the TAA-03 estimated that the Army would need between 300,000 and 330,000 soldiers to fight one major regional conflict.

Although typical peacetime missions such as peacekeeping and humanitarian assistance require fewer troops than major conflicts do, they place other difficult demands on Army forces. Some peacetime missions last for a long time. Thus, even though they do not require a large number of soldiers to deploy overseas at any given time, over a period of months or years the total number of soldiers involved can be substantial. And many peacetime operations require a very different mix of skills than those required for combat. Rather than destroying enemy forces (which is the focus of combat), peacekeeping emphasizes civilian control, policing, and community liaison. As a result, some units that participate in peacetime operations must train for several weeks afterward to regain a sufficiently high level of combat skills.

Despite those constraints, the nearly 780,000 deployable troops in the Army's active and reserve components should be sufficient to conduct smaller-scale combat operations or to fulfill U.S. obligations to multilateral peacekeeping missions. Indeed, the active Army alone contains more than 300,000 deployable troops, made up of 176,000 combat troops and 136,000 support personnel. Those full-time forces are many times larger than the number (around 50,000 from all services) that Administration policy says would be needed for operations short of a major regional conflict.

Force Requirements for Maintaining U.S. Presence Overseas

One final mission identified by the Administration that would require large numbers of Army forces is maintaining a military presence abroad to protect and advance U.S. interests. The two major permanent stations for Army personnel overseas are in Europe and South Korea. The U.S. presence in both areas has declined since the 1980s, but it is still sizable. The Army has about 64,000 troops stationed in Europe, down significantly from the 209,000 in 1989. It maintains some 27,000 soldiers in South Korea, a slight decrease from the 32,000 in 1989.

Because those soldiers represent only a small portion (less than 30 percent) of the deployable troops in the active Army, the bulk of the force is free to be sent elsewhere. Moreover, as long as sufficient troops remain in central Europe or South Korea to protect U.S. interests, the rest of the troops there are available to participate in lesser contingencies. Such troops frequently have an advantage in that they are closer to where such operations may occur. In the case of peacekeeping operations in Bosnia, for example, many of the U.S. Army personnel have come from forces stationed in Germany. Similarly, U.S. forces in South Korea may be better situated to deal with contingencies in the Pacific than troops stationed in the continental United States. Finally, some of the U.S. forces based overseas--particularly those in Europe, where tensions are currently low--would be available to take part in a major conflict should one erupt nearby. Indeed, large numbers of forces from Germany were sent to the Persian Gulf War in 1991.

Force Requirements for State Missions

During peacetime, the primary mission of the Army National Guard is to support state and territorial governors by carrying out the full spectrum of tasks authorized in state law. Those tasks typically include defense of the state from rebellion or disorder (that is, riot control); emergency and disaster relief; humanitarian assistance, such as aeromedical evacuation; and other efforts to support the community. The demands of state missions do not determine the size of the National Guard; the ability to conduct various federal missions forms the basis for establishing the size of the entire Army, including the Guard. That being the case, the Guard may not be the correct size or configuration to carry out its most common state missions--emergency and disaster relief.

Members of the National Guard are generally called to state duty only in small numbers and for short periods of time. There are several reasons for that practice. Paying for members of the Guard on state duty is a cost over and above a state's typical operating expenses. State budgets usually provide either a small, specific annual budget for the Guard--usually less than $10 million--or contingency funds available only under emergency conditions. As a result, Guard units are generally used in only the most extreme circumstances and only after other state and local resources are exhausted or overwhelmed. In addition, state and Guard leaders try to minimize the disruption in the civilian lives of Guard members by keeping them on state active-duty status for as short a time as possible.

For all of those reasons, members of both the Air and Army National Guard spent an average of less than one day per year on state active duty between 1987 and 1995.(7) In 1993, the peak year for state duty during that period, no single activation required more than 6 percent of the National Guard's total strength. It is true that in 1992, 1993, and 1994, natural disasters--including hurricanes, severe flooding, and an earthquake--combined with isolated events such as riots in Los Angeles to call large numbers of Guard forces into action. In each of those three years, about 30,000 members of the Guard were called to state active-duty status for an average of about two weeks.

Although 30,000 people represent only a small portion of the National Guard's total strength, some domestic emergencies can strain the resources available to an individual state. In particular, during operations in Florida in 1992 after Hurricane Andrew, almost half of the state's National Guard members were on state active duty at the same time. All told, Guard support extended for more than 80 days. Although federal assets were brought in after the President declared a state of emergency, and federal funds reimbursed some state expenditures, Florida still spent almost $29 million of its own money on tasks performed by the state National Guard in the aftermath of the hurricane.

The Army National Guard forces available to individual governors vary appreciably from state to state (see Figure 3). They range from as few as 600 soldiers in Guam to almost 18,000 in California. Of course, in cases of severe emergency, governors can ask the President to provide federal assets when state assets are overwhelmed, as occurred after Hurricane Andrew. (Presidents can call up members of the Army Reserve in such cases, but they generally choose to call on members of the active Army instead.)(8) Thus, states can sometimes receive assistance beyond the Guard forces within their borders.

Figure 3.
Number of Army National Guard Personnel, by State, at the End of 1996

SOURCE: Office of the Assistant Secretary of Defense for Reserve Affairs, Official Guard and Reserve Manpower Strengths and Statistics, FY 1996 Summary (1997).

1. The Army ranks fifth in the world based on total numbers (including the reserves). It ranks seventh in the number of active-duty soldiers.

2. See John C.F. Tillson and others, Review of the Army Process for Determining Force Structure Requirements (Alexandria, Va.: Institute for Defense Analyses, May 1996), for a comparison of the Army forces deployed to two MRCs in the Mobility Requirements Study Bottom-Up Review Update and the TAA-03.

3. Ibid.

4. Some of the assumptions of the TAA-03 that analysts have questioned may have been changed for the succeeding study--the Total Army Analysis 2005. Although the Army completed the bulk of the work for that analysis during the summer of 1997, the results were not publicly available at the time of this study.

5. Secretary of Defense Les Aspin, Report on the Bottom-Up Review (October 1993), p. 22.

6. Secretary Cohen has reiterated that point, stating that "U.S. forces must . . . be able to withdraw from smaller-scale contingency operations, reconstitute, and then deploy to a major theater war in accordance with required timelines." Secretary of Defense William S. Cohen, Report of the Quadrennial Defense Review (May 1997), p. 12.

7. Because of the way the National Guard Bureau maintains historical records, the Congressional Budget Office could not obtain data about activation rates for the Army National Guard separate from the Air National Guard. The Air National Guard is roughly one-third the size of the Army National Guard.

8. Members of the Army Reserve can be called up for involuntary active-duty service by the Secretary of the Army for a maximum of 15 days in any year. But because the two weeks of annual training must be counted against that total, and because the President does not typically mobilize Reservists for domestic emergencies, the 15-day limit effectively constrains the call-up of Reservists to assist in coping with state crises.

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