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Abstract
When and how do military interventions shape great powers’ grand strategies? Whereas prevailing theories of grand-strategic change emphasize international-structural or domestic-political factors, this study demonstrates that the process of warfighting reveals new information that reshapes states’ grand strategies.
Military interventions serve as crucibles of grand strategy that test the intervening state’s theory of security against the military and political realities of warfare. Three variables determine the vector of grand-strategic change subsequent to military interventions. First, international constraints drive decisions about levels of military means, or the proportion of national resources expended on defense. If a military intervention reveals that a state faces an elevated level of threat in its international environment, the state will increase the proportion of national resources dedicated to defense; if the intervention reveals a diminished threat level, the state will respond by decreasing its allocation of resources to defense. Second, domestic constraints shape estimates of the utility of military force in achieving political objectives and thus determine the scope of foreign-policy ends sought. If a military intervention reveals greater military capabilities and/or greater domestic-political support for the use of force abroad, a state’s propensity to use force is likely to increase with a commensurate expansion of grand-strategic ambition; the opposite result obtains when warfare reveals diminished political will or military capabilities. The interaction of these two variables accounts for variation among four possible grand-strategic vectors: militarization, rebalancing, retrenchment, or conservation. A third variable, the level of immediate threat revealed through warfare, predicts the extent to which post-war grand strategy will emphasize deterrence and defense against future contingencies similar to the war just fought.
This study develops and tests this theory using qualitative process-tracing methods in historical case studies of U.S. interventions in the Korean, Vietnam, and First Gulf Wars. Cumulatively, the case studies draw on tens of thousands of pages of primary source documents, many recently declassified, from six archives in two countries, as well as original interviews and secondary-source research. The conclusion presents evidence of the theory’s generalizability beyond the temporal and geographic scope of this study, and offers recommendations for U.S. foreign policy.
