Israels preventive attacks against Iraqs Osirak nuclear reactor in 1981 and Syrias Al-Kibar nuclear site in 2007 are often used to illustrate a fundamental precept of realismthat states will use military force to halt the rise of a rival state, especially if that rival attempts to gain a nuclear weapons capability. However, this approach does not fully explain the timing of such attacks, nor does it account for the consequences of violating another states sovereignty. In contrast to realisms emphasis on the material balance of power, constructivism focuses on how ideational factors, such as norms of appropriate behavior, shape and constrain a states behavior. By process tracing the events surrounding the attacks at Osirak and Al-Kibar, this thesis finds that the international norms of sovereignty, intervention, and non-proliferation had a strong influence over Israels behavior. It builds a normative theory of preventive attack that highlights the role that national identity, sanctions, and ethics play in counter-proliferation strategies. Finally, it concludes by offering policy recommendations for predicting future preventive attacks and leveraging international norms to halt nuclear proliferation.