The Secret Success of Nonproliferation Sanctions

Building on the rationalist literature on sanctions, this article argues that economic and political sanctions are a successful tool of nonproliferation policy, but that selection effects have rendered this success largely hidden. Since the late 1970s—when the United States made the threat of sanctions credible through congressional legislation and began regularly employing sanctions against proliferating states—sanctions have been ineffective in halting ongoing nuclear weapons programs, but they have succeeded in deterring states from starting nuclear weapons programs in the first place and have thus contributed to a decline in the rate of nuclear pursuit. The logic of the argument is simple: rational leaders assess the risk of sanctions before initiating a nuclear weapons program, which produces a selection effect whereby states highly vulnerable to sanctions are deterred from starting nuclear weapons programs in the first place, so long as the threat is credible. Vulnerability is a function of a state's level of economic and security dependence on the United States—states with greater dependence have more to lose from US sanctions and are more likely to be sensitive to US-sponsored norms. The end result of this selection effect is that since the late 1970s, only insulated, inward-looking regimes have pursued nuclear weapons and become the target of imposed sanctions, thus rendering the observed success rate of nonproliferation sanctions low. I find support for the argument based on statistical analysis of a global sample of countries from 1950 to 2000, an original data set of US nonproliferation sanctions episodes, and qualitative analysis of the South Korean and Taiwanese nuclear weapons programs.