Abstract: State’s legitimate self‑defence is considered Customary International Law and one of the essential rights a State can exercise, under the provisions of Article 51 of the Charter of the United Nations. The aim of this paper is to examine the conditions for exercising the legitimate self‑defence instead the analysis will focus on arguments that support the idea of including cyber attacks in the „armed attack” notion, that justifies the recourse to force by the victim State.

Keywords: Cyberspace; responsibility; ius ad bellum; ius in bello; imputability.