1. “Alliance Coercion and Nuclear Restraint: How the United States Thwarted West Germany’s Nuclear Ambitions,” International Security, Vol. 39, No. 4 (Spring 2015), pp. 91–129.
When does a nuclear-armed state’s provision of security guarantees to a militarily threatened ally inhibit the ally’s nuclear weapons ambitions? Although the established security model of nuclear proliferation posits that clients will prefer to depend on a patron’s extended nuclear deterrent, this proposition overlooks how military threats and doubts about the patron’s intentions encourage clients to seek nuclear weapons of their own. To resolve this indeterminacy in the security model’s explanation of nuclear restraint, it is necessary to account for the patron’s use of alliance coercion, a strategy consisting of conditional threats of military abandonment to obtain compliance with the patron’s demands. This strategy succeeds when the client is militarily dependent on the patron and when the patron provides assurances that threats of abandonment are conditional on the client’s nuclear choices. Historical evidence from West Germany’s nuclear decisionmaking provides a test of this logic. Contrary to the common belief among nonproliferation scholars, German leaders persistently doubted the credibility and durability of U.S. security guarantees and sought to acquire an independent nuclear deterrent. Rather than preferring to renounce nuclear armament, Germany was compelled to do so by U.S. threats of military abandonment, contradicting the established logic of the security model and affirming the logic of alliance coercion.
2. “Coercive Nonproliferation: Security, Leverage, and Nuclear Reversals” (Working Paper).
Under what conditions do states with nuclear weapons ambitions comply with demands for nuclear restraint? This paper argues that whether or not a nuclear aspirant gives up its weapons aims depends on two variables. The first is whether or not a nonproliferating state employs coercive leverage—meaning, it threatens to impose steep economic or military costs if the aspirant refuses to give up its bomb ambitions. If the nonproliferator does not employ leverage, then the aspirant’s bomb ambitions will persist. If the nonproliferator employs leverage, then the aspirant’s choices turn whether it expects to face security threats unaided after it exhibits nuclear restraint. If the aspirant receives security guarantees or expects to face a benign threat environment, then it will comply with demands for nuclear restraint in response to coercion. If neither condition prevails, then it will continue to seek a nuclear deterrent despite international pressure. These arguments are tested using analysis of co-variation across the universe of cases, and with detailed process tracing of U.S. nonproliferation efforts toward West Germany, Libya, South Africa, and Pakistan.
3. “Between Coercion and Compensation: Explaining Great Power Nonproliferation Strategy toward Allies” (Working Paper).
When do great powers use coercion to suppress allied proliferation, and when do they rely exclusively on “compensatory” strategies such as strengthened security guarantees and military inducements? To answer this question, this paper develops “selective coercion theory,” which posits that great powers will only apply coercive threats of abandonment and embargo when compensatory strategies have failed, and when the great power does not depend on the ally’s cooperation or survival. If compensatory strategies succeed, then coercion becomes unnecessary. If they fail, but the great power relies on its ally as a military partner or as a buffer state, then the great power will refrain from coercion. If the great power is not dependent on its ally, then it will apply coercive threats. To test this argument, the paper conducts detailed case studies of U.S. policy toward Japan, West Germany, and Pakistan, and Chinese policy toward North Korea.
4. “Assessing the Benefits and Burdens of Nuclear Latency” (Working Paper with Rupal Mehta and Rachel Whitlark).
How does nuclear latency affect states? Do states gain improved military security or political influence from the operation of uranium enrichment or plutonium reprocessing facilities, or do these facilities offer more burdens than benefits? Security studies provides conflicting perspectives on this question. Some scholars support the claim that nuclear latency functions as a virtual deterrent against would-be aggressors and a source of leverage in negotiations with adversaries and allies. But these claims contradict findings that states cannot deter military challenges without an operational arsenal, and that nuclear facilities may invite preventive strikes and nonproliferation sanctions. To resolve this debate, our paper employs large-n quantitative analysis on an expanded dataset of latency measures and a variety of both military and bargaining outcomes. Our findings suggest that latency is associated with greater conflict and coercive pressure, but that it also corresponds to greater commitments from allies, indicating mixed effects.
5. “The Determinants of Nuclear Latency” (Working paper with Rupal Mehta and Rachel Whitlark)
Why do states construct facilities for producing fissile material? Past studies of states’ nuclear decisions primarily addressed the determinants of nuclear weapons programs. Recent scholarship has moved beyond this debate by examining the steps along the proliferation pathway, especially the acquisition of technologies such as uranium enrichment and plutonium reprocessing (ENR), which enable states to achieve “nuclear latency.” But while researchers have investigated the international consequences of ENR proliferation, they have yet to examine its causes. This paper fills that gap in the existing literature by investigating whether states that constructed ENR facilities did so primarily to facilitate the nuclear weapons option, or whether latency was merely the byproduct of commercial needs. To pinpoint states’ motivations, this paper employs a combination of statistical and historical approaches. On the quantitative side, it uses revised time-series data on national ENR capabilities, together with data on economic and military characteristics, to assess the correlates of ENR acquisition. On the qualitative side, it employs detailed case studies of Japan, South Korea, Israel, and Egypt to establish the motivations for ENR programs. The paper concludes by deriving the implications of this research for international security and U.S. foreign and nuclear policy.