Abstract: Members of the nonproliferation regime give technical assistance to countries contemplating nuclear weapons. This is puzzling: it facilitates the behavior donors wish to stop, and other forms of concessions do not have this drawback. Why do it? I develop a model of uncertainty, bargaining, and nuclear proliferation. In it, assistance hastens acquisition time but also generates a signal about the recipient’s domestic nuclear capacity. This allows donor states to better calibrate other concessions to the recipient. In equilibrium, donor states sometimes find the information worth sacrificing bargaining leverage. However, despite providing information, assistance can cause proliferation if donors believe the recipient is competent but observe a false signal indicating incompetence. Strategic assistance from international institutions does not suffer from this problem, though a selection effect can make observational data appear to suggest otherwise.
