The article analyzes modern concepts of international security; the system of the law of international security is investigated in the light of the expansion of the subject of legal regulation, institutions of branch are determined. The study of the content of the sectoral principles of the international security law is conducted and it is justified that a new principle of the international security law is being formed: the principle of providing protection assistance (the principle of protection) against extremist (terrorist) actions, threatening the sovereignty of the state.