Date of Award
8-13-2025
Degree Type
Thesis
Degree Name
Master of Philosophy (MPHIL)
Discipline
Social Sciences
Department
Government and International Affairs
First Advisor
Prof. ZHANG Baohui
Second Advisor
Prof. YANG Shen
Abstract
Classical nuclear deterrence theory suggests that nuclear powers could be tempted to strike first in asymmetric dyads (dyads in which only one side is a nuclear power). However, in the Ukraine war, a nuclear-armed Russia has not deployed tactical nuclear weapons on the battlefield, even at times when its military struggles on the ground with unfavorable balance. Why has Russia not used its nuclear weapons, especially after repeated threats of using them? What conditions make it rational for states to cross the nuclear threshold in asymmetric dyads? What discourages them from using nuclear weapons while possessing nuclear monopoly?
Expected utility models of war and nuclear deterrence, which flourished during the Cold War, are largely logically equivalent to realism. Both approaches focus on states’ military power and tend to neglect states’ interdependence. While this focus may be able to explain states’ decision-making during the Cold War, the lack of systematic exploration of the impact of interdependence on states reduces the contemporary explanatory power of war models that are built on the expected utility theory. In particular, existing formal models assume that the cost incurred from the (conventional and nuclear) military balance is the major parameter influencing states’ decision-making regarding (nuclear) escalation. Consequently, these models tend to inaccurately expect a rational use of tactical nuclear weapons in the war in Ukraine. To fill the gap, this thesis investigates the role of interdependence in the Ukraine war from the perspective of third-party states’ economic influence over the nuclear power––that is, the nuclear power’s economic calculations. This research is guided by a formal game-theoretic model and tested using qualitative methodologies, including process tracing and an analysis of observable implications.
This thesis shows that the threatened economic sanctions by third-party states very likely served as a cost that disincentivized Russia’s nuclear use and seemed to have significant weight in states’ decision- making. In addition, the conflict dynamic of the case generally fits with the description of the model proposed in this thesis and hence demonstrates the coherence of the model. Firstly, evidence suggests that the balance of conventional power on the ground shaped Russia’s risk attitude and thus its evaluation of costs and inclination toward nuclear escalation. Secondly, third-party states have attempted to resolve the information problem in order to raise the expected cost of nuclear detonation for Russia.
Language
English
Copyright
The copyright of this thesis is owned by its author. Any reproduction, adaptation, distribution or dissemination of this thesis without express authorization is strictly prohibited.
Recommended Citation
Chiu, C. C. (2025). Rational tactical nuclear first use in asymmetric dyads and the states' calculus of costs in an era of interdependence: A game-theoretical approach (Master's thesis, Lingnan University, Hong Kong). Retrieved from https://commons.ln.edu.hk/otd/251/