When does signaling with nuclear weapons help states achieve their political aims during international crises? Rather than exploring the coercive effect of the background threat of nuclear destruction, this paper develops a military signaling theory of nuclear coercion. The theory argues that military signals using nuclear-capable forces could lead to favorable crisis outcomes by manipulating the perceived risk of nuclear escalation, but such shifts in the perceived likelihood of nuclear war are not constant across different crises. Rather, the effect of militarized nuclear signals on crisis outcomes is moderated by the balance of military power, including both nuclear and conventional forces. Using a novel dataset on all episodes of military signals employing nuclear-capable forces in crises, I find supportive evidence for my expectations. Militarized nuclear signals increase a coercer’s chance of achieving crisis aims when facing a conventionally superior non-nuclear target, decrease it when confronting an adversary with superior nuclear forces, and have no measurable effects on crisis outcomes if a non-nuclear target possesses conventional military superiority. Contrary to my expectation, however, coercive signals using nuclear-capable forces reduce the chance of securing crisis aims when the balance of conventional forces favors a nuclear-armed target.

Dr Kyungwon Suh is a Lecturer at the Strategic and Defence Studies Centre at the Australian National University. He received a Ph.D. in Political Science from Syracuse University in 2022. His research interests include nuclear weapons, interstate coercion, alliance politics, and great power politics. His previous research has been published in Journal of Peace Research and Journal of Conflict Resolution.