It is a very fact that modern Public International Law strictly prohibits either any threat of armed force by any sovereign political entity (state) or use of armed force by any state acting without the authorization of the UNSC on the foundation of the VII Chapter of the UN Charter. In other words, the use of force, including an armed (military) intervention, is possible only under the umbrella of the UN Charter but after the authorization by the UNSC in accordance to the idea of collective security. Here, two questions arise: What is Public International Law and What is collective security?
International law is also known as Public International Law to distinguish it from Private International Law, which does not deal with relationships between states. Public International Law is understood as a system of rules that are binding on states, and thus define the relationships between states and/or other political entities and subjects in international relations and world politics. Law is a set of public and enforceable rules. In the case that there is no world legislature, international law draws on a number of sources like treaties, custom, generally accepted principles, and the practice based on the decisions by the international courts. Public International Law is usually seen as the best means of establishing order through respect for moral principles and, therefore, Public International Law makes possible the peaceful resolution of international conflicts. In general, Public International Law is a system of law regulating the interrelationship of sovereign states and their rights and duties with regard to one another.
Who has the right of power to determine disputes relating to Public International Law? International Court of Justice or The World Court. This court at the Hague is consisting of 15 judges elected for 9-year terms of office and was set up by the UN in succession to the Permanent Court of International Justice, and all members of the UN are automatically parties to the Statute of International Court of Justice. This court as well as can give advisory opinions (advisory jurisdiction), which do not bind the parties but are of great persuasive authority.
United Nations Security Council meeting at its headquarters in New York
The idea of collective security is an integral segment of Public International Law based on the notion that aggression can best be resisted by united action taken by a number of states but covered by the international law at least to a certain extent.