NATO’s Nuclear Types: Vulnerability, Defense Investment, and Alliance Strategy Preferences

Members of nuclear alliances face myriad and complex demands. They must ensure that their nuclear-armed patron maintains adequate capabilities and resolve, while avoiding entrapment and entanglement. How, then, do states manage these competing needs? To address this question, we develop a typological theory of nuclear alliance members. We argue that a state’s vulnerability to a nuclear adversary and relative military spending/capacity ultimately determine its position within security alliances. This heterogeneity affects which deterrence and assurance needs various states will prioritize. Consequently, based on their type, alliance members will choose different strategies for managing their nuclear threat environment. Such choices range from hedging between their nuclear-armed patron and their adversary to seeking independent capabilities to influence their patron’s posture. We test these arguments using a public opinion survey conducted in ten current NATO member countries, fielded during a period of heightened nuclear salience in the Russo–Ukrainian War. The results reveal strong cross-national variation in public preferences regarding nuclear alliance management, thereby demonstrating the value of our typology in understanding dynamics within NATO.