Columbia International Affairs Online: Working Papers

CIAO DATE: 01/2010

Beyond Optimism and Pessimism: The Differential Effects of Nuclear Proliferation

Matthew Kroenig

November 2009

Belfer Center for Science and International Affairs, Harvard University

Abstract

What is the effect of the spread of nuclear weapons on international politics? The scholarly debate pits proliferation optimists, who claim that “more may be better,” against proliferation pessimists, who argue that “more will be worse.” These scholars focus on the aggregate effects of nuclear proliferation, but never explicitly consider the differential effects of the spread of nuclear weapons. In other words, they do not examine whether nuclear proliferation may threaten some states more than others. I propose a theory of nuclear proliferation that examines the differential effects of nuclear proliferation. I argue that the threat nuclear proliferation poses to a particular state depends on that state’s ability to project military power. The spread of nuclear weapons is worse for states that have the ability to project conventional military power over a potential nuclear weapon state primarily because nuclear proliferation constrains their conventional military freedom of action. On the other hand, nuclear proliferation is less threatening to, and can sometimes even improve the strategic environment of, states that lack the ability to project power over a potential nuclear weapon state, because the spread of nuclear weapons disproportionately constrains other, more powerful states. This article contributes to our understanding of the consequences of nuclear proliferation and contains important implications for nuclear nonproliferation policy.