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RAND Review
Army Stretched Thin
There’s No Easy Way Out for the Nation
By Lynn Davis and J. Michael Polich
Lynn Davis, a political scientist at the RAND Corporation, was U.S. undersecretary of state for arms control and international security affairs from 1993 to 1997. Defense analyst Michael Polich is a senior behavioral scientist at RAND.
The United States faces an enormous challenge in having to provide military forces for sustained overseas operations while protecting the American homeland and standing ready for other crises that may require rapid response. Driven by the wars in Iraq and Afghanistan, the increased operational tempo of the last four years has led to lengthier and more-frequent deployments of soldiers and units across the entire U.S. Army, putting stress on both its active and reserve components.
Today, the bulk of the active-duty army is either in Iraq, returning from Iraq, or preparing to go to Iraq. The formerly part-time soldiers in the National Guard now account for about 40 percent of the brigades deployed to Iraq and Afghanistan. And since the war began in Iraq two years ago, the length of a standard mobilization for reserve units going there has risen well above the one-year goal that was originally intended.
These events have placed a growing strain on the U.S. Army as it seeks to train its soldiers and to maintain a pool of units ready to respond rapidly to new contingencies. This situation confronts the nation with urgent questions about the proper size of the army’s active and reserve forces, about the optimum number and types of combat units needed to sustain high levels of overseas deployments while maintaining readiness for other missions, and about the effects on soldiers and units stretched thin by the repeated, rapid rotations.
What emerges from our analysis is a picture of the difficult trade-offs the army faces today. |
We have examined various ways in which the army might respond to the current and future demands upon its forces. We have also gauged the likely long-term effects of several policy options on army combat brigades. The options utilize brigades from the Active Component (AC) and Reserve Component (RC) operating under either a standard rotational schedule or an intensified one. (The RC includes both the U.S. Army Reserve and the National Guard, although only the National Guard has combat brigades.)
As illustrated in the centerpiece, what emerges from our analysis is a picture of the difficult trade-offs the army faces today, assuming a world in which high levels of overseas rotations continue. The difficult trade-offs could augur major changes in the future size, structure, cost, and management of the active and reserve forces. The challenge is daunting. We see no viable option free of substantial risks, sacrifices, or both.
Rough, but Ready?
In our analysis, we focused on two outcome measures that characterize the army’s ability to fulfill its missions over time: (1) “time at home” between deployments for active-duty brigades, and (2) the number of “ready” active-duty brigades.
Time at home is important because of its broad ramifications for unit training and soldier well-being, recruitment, and retention. The number of ready units is a metric for assessing the nation’s defense posture and the army’s ability to respond rapidly to new threats.
These two outcome measures depend on several factors that could vary simultaneously:
- Size of the operational requirement: We analyzed a range of requirements, from 8 brigades to 20 brigades required at any given time. As a point of reference, the army’s requirements have grown over the past couple of years from 12 brigades to 17 brigades in Iraq and Afghanistan alone.
- Army force size and structure: We examined the effects of different operational requirements on the baseline force (pre-2004) and the planned (or “transformed”) force, which is expected to be in place by 2007 in the AC and 2010 in the RC. We also examined the effects of relying on a future force that might include an expanded AC or might have a different mix of RC units than currently planned.
- Utilization policies: We compared variations in the frequency of reserve unit mobilizations and in the amount of preparation time given to the units prior to deploying. Under current policy, the goal is for reserve units to be mobilized for a maximum of one year out of every six. Given the need for training during this year of mobilization, we assumed that reserve units would train for six months and deploy for six months. We modified this policy hypothetically to allow for more-intensive utilization of the reserves in all three respects, such as mobilizing the reserves one year out of every five years, training them for only three months of that year, and extending their deployments to nine months.
The burden is eased only slightly by the army’s plans for transformation. |
We also accounted for the three types of army combat brigades now being planned by the army for its transformed force: heavy, medium, and infantry. Heavy brigades have armored vehicles for maximum protection and firepower. Medium brigades have wheeled vehicles for mobility and versatility. Infantry brigades typically lack an extensive complement of ground vehicles. The classification is important because the different types of units are specialized for particular combat missions and environments, and there are limitations on the extent to which the units can substitute for one another.
In our analysis, we assumed that heavy and medium brigades could substitute for one another. Therefore, we combined them into a category called “heavy-medium” brigades. On the other hand, we generally assumed that infantry units could not do the job of heavy-medium units, though we considered cases where the types of units were interchangeable in meeting the overseas requirements.
Few Options
Our analysis began by considering what would happen if the U.S. Army relied solely on its supply of active-duty brigades. We weighted the in-theater requirement toward heavy-medium brigades, in line with the emphasis currently placed on deploying these types of brigades to Iraq and Afghanistan. For political reasons, we subtracted certain brigades from the pool of available rotating brigades. From the pre-2004 force, we subtracted one brigade, assigning it to Korea. From the transformed force, we subtracted two brigades, assigning one to Korea and one to Europe.
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Figure 1 shows the results, both for the pre-2004 force of 32 rotating active-duty brigades and the post-transformation force of 41 rotating active-duty brigades. In both cases, the inventory of heavy-medium brigades falls under considerable stress when sustained deployment requirements exceed 10 combat brigades. The burden on heavy-medium brigades is eased only slightly by the army’s plans for transformation, because those plans call for the addition of mostly infantry brigades.
At larger requirements (12 through 20 brigades), the time at home for heavy-medium brigades drops to less than two years. Two years of time at home is a well-established army goal for refreshing, refitting, retraining, and thus “readying” units between subsequent deployments.
Some improvement could be made by permitting units of any type to substitute for one another, such as sending infantry units in place of heavy-medium units. This change would equalize the strain across all army units. As the requirements rise above 14 combat brigades, however, both the heavy-medium and infantry units would begin to face less than two years at home. At these high levels of demands, the nation would be left with few brigades primed and ready for other needs.
We then examined the potential of using the reserve brigades to extend the time at home for the active brigades and thereby to increase the number of ready active brigades. We stipulated the use of the entire post-transformation supply of 11 heavy-medium reserve brigades to fulfill a sustained deployment requirement of 16 brigades, of which 11 are specified to be heavy-medium.
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Figure 2 shows the results for time at home for the active-duty heavy-medium brigades. Their time at home remains substantially below two years no matter how hard the reserves are pushed. We initially assumed that the army would mobilize the reserves for one year out of every six, in line with defense department policy. We then investigated a series of modified RC policies, such as more frequent mobilizations (one year out of every five, four, or three) and reduced preparation times (with longer deployments). We found these modifications to be somewhat helpful but still insufficient, even in combination, to bring the time at home for AC heavy-medium brigades up to the two-year threshold.
To meet its goal of two years at home for all AC brigades between deployments, therefore, the army would need to take further steps. One possible approach would be to increase the number of AC and/or RC heavy-medium units beyond those in the army’s transformation plan — a costly but conceivable solution.
Another approach would be to use infantry and heavy-medium brigades interchangeably and to use all AC and RC brigades interchangeably. In this case, though, the nation would have to accept the appreciable risks of assuming that any type of brigade could accomplish any type of mission and that each of the reserve brigades would be equal in capability to the active brigades.
Many Risks
Each policy alternative involves significant costs, risks, or both. We have posited a series of future conditions that raise progressively tougher questions for the nation. Where possible, we have proposed how the army might adapt to meet the immediate requirements and to sustain its forces over the longer term. But in most of the cases that we could envision, the future conditions would present the army — and the nation — with notable risks of one kind or another.
Time at home for the active-duty heavy-medium brigades remains substantially below two years no matter how hard the reserves are pushed. |
Suppose, initially, that overseas rotation requirements drop back to 10 brigades. All AC units would have at least two years at home between deployments. The army would have a full stock of more than 20 ready combat brigades, of which at least 11 would be heavy-medium brigades.
The question for the nation is whether policymakers are comfortable basing future army planning on this rosy scenario of consistently lower levels of overseas rotational requirements. This assumption could be plausible if we view the current requirements in Iraq and Afghanistan as an aberration or something to be endured for only a short time now or periodically in the future.
Alternatively: What if high overseas rotation requirements — of 14 to 20 brigades — continue for some time? The army would experience serious problems with active-unit readiness. The nation would have few, if any, ready AC brigades to turn to in a crisis. Transforming the army as planned would alleviate the strain a bit. But transformation would be largely in the future, would bring its own uncertainties, and could not meet the full demand for rotational forces by itself.
The nation could decide to live with low levels of active-unit readiness — if it assumed that the army would only rarely need to respond quickly to contingencies with large numbers of forces, either overseas or at home. This course presumes that international or domestic contingencies would not require the army to do much beyond supporting its current level of overseas rotations.
What if the risks are too high for the army to plan for low levels of contingency requirements? There are two possible adaptations. First, the army could turn to the reserves and plan to utilize them at reasonable rates, such as mobilizing RC brigades for one year out of every six years. But RC units would still cover only a modest portion of the total requirement for overseas forces.
Second, the army could assume that any AC or RC unit could perform the mission demanded by any contingency. This course would carry considerable risk if a theater environment were not benign or if a mission required armored protection or ground mobility. To date, the army has hedged against these risks by deploying predominantly heavy-medium forces to Iraq. And even if full flexibility were possible among all types of units, AC time at home would still dip below two years if the total overseas rotational requirements were to increase beyond about 17 brigades.
What if it is too risky to assume that AC and RC infantry and heavy-medium brigades can substitute for one another in future missions? We see only two realistic options. One is for the army to forgo its transformation plans to convert some of its RC heavy-medium units to infantry units. This option would also require the army to find the financial resources to make all 25 of its existing RC heavy-medium units equal in readiness to AC heavy-medium brigades.
Alternatively, the army could add more AC heavy-medium brigades. This could be accomplished either by adding units or by changing the mix of units in the transformation plan. This option would require many billions of dollars beyond the current plan and would take years to achieve.
To decide among these options will require the nation to confront a number of trade-offs. The trade-offs pertain to the army’s reliance on the AC versus the RC; the risks to the nation if the army has few ready units for new contingencies; the training required of army units for different types of operations; and the resources available for the AC, the RC, or both.
Our analysis suggests that none of the trade-offs will be easy. No single policy is likely to meet all goals. Each option involves sacrificing something important or incurring substantial costs. 
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