The Regulation of Cyber Operations Below the Threshold of Article 2(4) of the Charter : An Assessment of Rule 4 of the Tallinn Manual 2.0

Abstract: The cyber domain poses great challenges to the existing international law framework, resulting in the international community's frustration in finding sustainable long-term solutions to the international regulation of cyberspace. This thesis reflects upon foundational concepts of the jus ad bellum framework, such as State sovereignty and the use of force. The principal issue discussed in this thesis is the emergence of a customary international norm prohibiting violations of sovereignty, essentially targeting lowintensity cyber attacks. Violations of sovereignty were classified as a primary rule in Rule 4 of the Tallinn Manual 2.0 (2017), which sparked a debate about the rule's true existence as a customary norm. This thesis assesses whether violations of sovereignty can currently be extrapolated as a primary rule of customary international law. It thereafter discusses the need for such a rule, as well as the risks of such a rule emerging as a customary norm.