For nearly seventeen years, targeted killing has been lauded by the United States as the optimum method of disrupting terrorist activities carried out by al-Qaeda and ‘affiliated forces’ not only in Afghanistan and Iraq, but outside the immediate zone of hostilities in Pakistan, Somalia, Yemen, Libya, Niger and Syria. While thousands of civilians and suspected militants have been killed in such strikes, their effectiveness in disrupting terrorist activity appears minimal. This thesis investigates the relationship between targeted killing, the doctrine of Kriegsraison (which posits that states may use all means considered necessary, however unlawful, to protect the security of the state), and international law. It does so in order to examine how targeted killing and Kriegsraison harm international law at the same time as they employ international law as a validating tool. The thesis undertakes a theoretical and doctrinal study of international law using a critical approach, and clarifies the legality of the targeted killing programme and how the political actions and context that influence the United States’ legal actions and interpretations have led to the return of Kriegsraison. Given Kriegsraison’s self-judging nature, it is particularly damaging to the international legal order and international relations. The thesis engages directly with the questions raised by the United States use of armed drones as the main method of carrying out the targeted killing programme. Furthermore, through an assessment of the domestic context that informs the United States’ ambivalent relationship with public international law, the thesis contends that the resurrection of Kriegsraison is a violent expression of U.S. legal imperialism, and of the United States’ long-held belief that it exists in its own, permanent state of exception. Finally, the thesis concludes that Kriegsraison itself operates in a state of exception inside the liberal order, often through the harnessing of international law rules.