The thesis will be a comparative study concerning cyberdeterrence as it is carried out by the U.S. and the EU. The emphasis will be on discovering what differences exist between the two approaches to cyberdeterrence, while also analyzing the shared cyberdeterrence policy that exists through NATO. The aim will be to compare the cyberdeterrence policies of the U.S. and the EU by analyzing the respective factors that shaped these policies, their theoretical underpinnings, as well as the cyberdeterrence capabilities of both parties. Furthermore, the thesis will provide a review of traditional approaches to deterrence, such as nuclear, then attempt to show how the cyberdeterrence policies of the U.S. and the EU fit within their broader approach to security and deterrence. The research will be guided by the following questions: 1) Do the U.S. and EU differ in their understanding of cyberdeterrence? If so, what are these differences and how are they reflected in policies?; 2) What factors, threats, contributed to the development of the respective policies? If similar threats exist, what other factors might have lead to the generation of alternative cyberdeterrence responses?; 3) What differences exist between NATO’s collective cyberdeterrence approach and the domestic approaches provided by the U.S. and the EU? If there are differences, why do they choose not to implement the same collective policy that is held domestically?