Objectives:
The aim of the study was to provide an answer as to whether, on the basis of the provisions of the Charter of the UN, the states associated with the UN have sufficient legal provisions to conduct self-defence in the event of an armed attack directed by another state or multiple states.

Methods:
Critical analysis and synthesis of legal documents and research literature resulting in conclusions. Key book positions as well as academic articles, domestic and foreign, were analysed.

Results:
The result of this study is the thesis that Article 51 of the UN Charter, despite its generality, allows, from a legal point of view, any State to act in self-defence, even in situations not envisaged in the in the Charter. However, given the current security situation, a discussion and reflection on this institution of law is needed in order to be prepared to apply it in the face of threats such as hybrid, cyber or conducting operations in the space domain.

Conclusions:
The right to self-defence should be counted among the pillars of international security comprising the security system of each state. Thanks to this institution, the state subject is equipped with the legal attribute of being able to use armed force in international relations. However, it is beyond dispute that the legal construction of self-defence has been used in a way that deviates from the noble ideals of the Charter through the declaration of the Russian Federation on acting in self-defence in order to 'legalise' an armed attack on Ukraine.