Are U.S. Military Interventions Contagious over Time? Intervention Timing and Its Implications for Force Planning

When Department of Defense DoD force planners use integrated security constructs and multiservice force deployment scenarios to estimate force requirements, their models assume that military deployments by U.S. forces occur as independent events that are not systematically correlated over time i.e., that they are serially uncorrelated. However, the U.S. experiences in Southeast Asia during the 1960s, the Balkans during the 1990s, and the Middle East since 2001 suggest, at least anecdotally, that military interventions may not be serially independent. It is possible, instead, that they demonstrate temporal dependence, in which the likelihood of an event in one period is affected by the frequency of similar events in past periods. Temporal dependence would tend to produce event clusters as each incidence of a given event increases the likelihood of similar events in the near future. If U.S. military interventions do in fact demonstrate temporal dependence, one would expect them to occur in clusters. This would result in a very different demand signal for U.S. military capabilities than the current DoD approaches to force planning, which assume serially uncorrelated interventions, produce. This study assesses whether there is empirical evidence of temporal dependence in U.S. military interventions.