In the complex landscape of international relations, the right to self-defence is fundamental in shaping state action when faced with aggression. This right is set within the framework of international law through the United Nations (UN) Charter in article 51 (UN Charter, 1945), which delineates the limits to how states can respond to threats to their sovereignty and security. Recent events, such as the Iran-Israeli conflict, have reopened discussions on the application and interpretation of the right of self-defence. As tensions escalate and geopolitical dynamics evolve, it is essential to take a closer look at the legal foundation of states’ notion of self-defence and its relevance in contemporary conflicts. This article examines the nature of self-defence in international law and explores its core elements through an analysis of the recent retaliatory spiral that started with Israel’s strike on Iran’s embassy in Syria.