Nuclear balance and extended deterrence: evidence from cold war superpower alliances

Abstract Does a favorable nuclear balance of power strengthen the credibility of extended deterrence against nuclear-armed opponents? This “superiority-credibility” thesis has long been supported by scholars and policymakers, but surprisingly little attention has been paid to testing this idea empirically. This paper tests the thesis using conflict initiation data from the superpower-led alliances during the Cold War. My statistical analyses find that there is no evidence that the degree of a superpower patron's military nuclear advantages vis-à-vis another nuclear-armed superpower significantly reduces the likelihood that the patron's allies become targets of militarized disputes. This finding holds across multiple model specifications and a wide range of measures of the balance of nuclear forces. This paper contributes to theoretical debates on the role of the nuclear balance in interactions between nuclear-armed states and policy debates on the size of the American nuclear arsenal in the coming era of deterring 2 nuclear-armed peers.