- Are military interventions serially independent, as assumed in existing force planning processes? Or do they tend to cluster in time due to temporal dependence?
- What are the implications of clustered deployments for force planning?
Current DoD force planning processes assume that U.S. military interventions are serially independent over time. This report challenges this assumption, arguing that interventions occur in temporally dependent clusters in which the likelihood of an intervention depends on interventions in the recent past. The author used data on 66 U.S. Army contingency and peacekeeping deployments of at least company size between 1949 and 2010 and found evidence of temporal dependence between military interventions even when controlling for political, economic, and other security factors. However, the results also suggested that clustering is affected by the nature of the geopolitical regime and is stronger at certain points than others, for example, after the Cold War as compared to during the Cold War. The results suggested that as few as two military interventions above average is often enough to trigger interventions in subsequent years. Because current planning processes address only the direct force demands of a given deployment and ignore the heightened risk for additional demands created by temporal dependence, these processes may project force requirements that understate the demands placed on military deployments during a period of clustered interventions. This analysis suggests that DoD should consider modifying the integrated security constructs to incorporate serial correlation of interventions, making assumptions about the nature of the current or future geopolitical regime explicit, and assessing whether the existing set of force planning frameworks reflects the spectrum of potential future geopolitical regimes.
U.S. Military Interventions do exhibit temporal dependence under certain geopolitical regimes
- Army interventions do exhibit evidence of temporal dependence that increases the chances they will occur in dependent clusters rather than following the serially independent distribution assumed in force planning processes.
- Temporal clustering may exist at certain points and not others, as influenced by the international and domestic factors that characterize the prevailing geopolitical regime.
Taking Temporal Dependence into Account Can Help Planners Avoid Underestimating the Demand for Personnel and Skill Sets
- Force planning incorporating temporal dependence must address both the direct force demands of a given deployment and the heightened risk of future demands due to temporal correlation. Force planning that does not address both components risks generating force estimates that underestimate the number of interventions, the demands on military personnel, and the force size needed to meet demands during clustered interventions.
- The fact that U.S. military interventions tend to cluster together in time implies that force planning frameworks that assume a serially uncorrelated pattern of interventions, such as the integrated security constructs, may understate actual requirements for forces and capabilities during a period of clustered interventions. This would create operational and strategic risk, and DoD should consider modifying the integrated security constructs to incorporate serial correlation of interventions.
- The observation that the likelihood and clustering of interventions are sensitive to the character of a geopolitical regime suggests that the pattern of future military operations projected by a force planning framework reflects important, if implicit, assumptions about the nature of the future geopolitical regime. It would be prudent for DoD to make these assumptions explicit and consider whether the existing set of force planning frameworks reflects the spectrum of potential future geopolitical regimes.
- Temporal dependence can also be included qualitatively in force planning processes, by incorporating in planning documents an extended discussion of the concept and its implication; how it relates to intervention duration, frequency, and concurrency; and a description of the role the geopolitical regime plays in the likelihood and strength of clustering.
- Policymakers and planners may need to identify the international, geopolitical, and domestic factors that make clustering more likely at certain points rather than others and be able to diagnose when major shifts in geopolitical regime that will have implications for temporal clustering have occurred.
Table of Contents
Defining Temporal Dependence: A Review of Existing Evidence
Testing for Temporal Dependence
Implications for Force Planning
Conclusion and Next Steps
The research described in this report was sponsored by the United States Army and conducted by the RAND Arroyo Center.
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