There is more than one reason why South-East European States should clarify their public positions on the applicability of sovereignty as a principle or as the rule of international law while addressing the growing ambiguity in cyberspace. The article argues that strategically and legally it is in the SEE States’ interest to step up and fill the vacuum in ever needed opinio iuris on the applicability of sovereignty in cyberspace, particularly after some leading NATO States took an opposing course on the issue. Explaining the evolution in cyberspace and how this affects the Westphalian concept of sovereignty under international law the article introduces the importance of the main thesis. It then provides the rationale for the argument and explains why it is in the SEE States interest to act and express their position on the applicability of sovereignty in cyberspace under international law.