Escalation of hostile cyber operations between States and other subjects of international law is leading to the emergence of a brand-new branch of public international law that deals with them. Dynamic technological development over the past decades led to the creation of cyberspace, a novel dimension in which States can interact, collaborate, and compete. This has given rise to an array of legal questions regarding the application of existing international rules and the need to create new ones. This book lays out the full context of that process, highlights its outcomes, and anticipates its future evolution. While we haven't yet crossed the point of recognition of the emerging practices on hostile cyber operations between States as a Special Regime of Public International Law, we can already discern early elements of the framework establishing specialized interpretative rules and unique legal norms that apply exclusively in international cyberspace, giving us a sense of what's coming. “I extend my highest praise for this book. It is a great, panoramic source of insight into the subject of hostile cyber operations between States in public international law. This new phenomenon creates questions on application of existing laws and potential new ones. The author skillfully lays out current challenges and possible future developments.” – Prof. Dr. habil. Dr. h.c. mult. Karol Karski Head of the Department of Public International Law Faculty of Law and Administration University of Warsaw, Poland