Despite the COVID-19 pandemic and perhaps in some ways because of it, conflicts of interest between the United States and China seem only likely to increase in the coming years. As conflicts of interest between these two states increase, one central question for scholars and policy-makers is the probability of different causal mechanisms whereby a conflict of interest generates a crisis and the crisis becomes a limited, conventional or even nuclear war. Another important and closely related question is which allies Washington and Beijing can count on to do what as these conflicts of interest grow. Unlike China, the United States has alliances that span the world, with formal defence commitments throughout Europe and Asia. If alliances do more than aggregate but substantially multiply U.S. power, exactly what do they bring to the table?
“Divided priorities: why and when allies differ over military intervention” by Ronald R. Krebs and Jennifer Spindel is an important piece of research. The authors challenge the validity of the claim that weaker allies value their patrons’ hawkish postures in distant conflicts. This claim, first put forward by Glen Snyder in Deterrence and Defense (1961), reasons that a patron’s limited foreign interventions make allies feel reassured of their own defense commitment with their patron state: if their benefactor is willing to fight for places of trivial intrinsic and strategic importance, it will surely also be willing to fight for them if the necessity arises.
The defining characteristic of modern international politics is unipolarity. Never before has one state achieved such a remarkable lead in economic capacity and military capability. American power today is unrivalled and durable, even after the economic crisis of the last decade. It will be a very long time before another state qualifies as a peer competitor.