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.Starting in the 1970s and continuing to sanctions against Iran in the present day, US policy-makers have long considered sanctions central to US efforts to halt nuclear proliferation and have employed them regularly. Many scholars of nonproliferation are similarly optimistic about the role of sanctions, arguing they are an important component of the nonproliferation policy toolkit. 1 Despite their centrality to US nonproliferation policy, the efficacy of these efforts-which include financial and trade restrictions, economic and military aid cutoffs, termination of peaceful nuclear cooperation, as well as threats to weaken military alliance relationships-remains

We examine the effect of nuclear weapons on interstate conflict. Using more appropriate methodologies than have previously been used, we find that dyads in which both states possess nuclear weapons are not significantly less likely to fight wars, nor are they significantly more or less belligerent at low levels of conflict. This stands in contrast to previous work, which suggests nuclear dyads are some 2.7 million times less likely to fight wars. We additionally find that dyads in which one state possesses nuclear weapons are more prone to low-level conflict (but not more prone to war). This appears to be because nuclear-armed states expand their interests after nuclear acquisition rather than because nuclear weapons provide a shield behind which states can aggress against more powerful conventional-armed states. This calls into question conventional wisdom on the impact of nuclear weapons and has policy implications for the impact of nuclear proliferation.

D o foreign occupiers face less resistance when they increase the level of native governing authority?Although this is a central question within the literature on foreign occupation and insurgency, it is difficult to answer because the relationship between resistance and political devolution is typically endogenous. To address this issue, we identify a natural experiment based on the locally arbitrary assignment of French municipalities into German or Vichy-governed zones during World War II. Using a regression discontinuity design, we conclude that devolving governing authority significantly lowered levels of resistance. We argue that this effect is driven by a process of political cooptation: domestic groups that were granted governing authority were less likely to engage in resistance activity, while violent resistance was heightened in regions dominated by groups excluded from the governing regime. This finding stands in contrast to work that primarily emphasizes structural factors or nationalist motivations for resistance.

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