Collective security is the main purpose of the United Nations, just as it was the main purpose of its predecessor, the League of Nations. What does collective security mean? Under general international law the principle of self-help prevails. The protection of the legal interests of the states against violations on the part of other states is left to the individual state whose right has been violated. General international law authorizes the state, i.e., the individual member of the international community, to resort, in case of a violation of its rights, to reprisals or war against that state which is responsible for the violation. Reprisals and war are enforcement actions. Insofar as they are reactions against violations of the law, and authorized by it, they have the character of sanctions. We speak of collective security when the protection of the rights of the states, the reaction against the violation of the law, assumes the character of a collective enforcement action.