Collective Security and Collective Self-Defense Under the Charter of the United Nations *

Collective security is the main purpose of the United Nations, just as it was the main purpose of its predecessor, the League of Nations. Self-defense is that minimum of self-help which, even within a system of collective security based on a centralized force monopoly of the community, must be permitted. The decentralized enforcement actions to be taken within the system of collective security established by the Covenant were true sanctions reactions against violations of the law. The Charter must restrict the centralization expressly by authorizing the members to use force as self-defense. Collective self-defense under Article 51 of the Charter of the United Nations is similar to collective security under Article 16 of the Covenant of the League of Nations. The measures of collective security taken under Chapter VII of the Charter are centralized actions of the Organization, whereas the process of collective self-defense is a decentralized reaction against armed attack.