Article 51 Nothing in the present Charter shall impair the inherent right of individual or collective self-defence if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security.

B. Article 2 (4) - Prohibition of threat or use of force in international relations. Article 2 (4) of the Charter prohibits the threat or use of force and calls on all Members to respect the sovereignty, territorial integrity and political independence of other States.

These exceptions are the use of force by the Security Council under Chapter VII in case of a “threat to peace, breach of peace and act of aggression,” and the right to use force under Article 51 in individual or collective self-defense.

The UN Charter The UN Charter contains both the principle prohibiting the use of force and exceptions to it. These rules concern individual States. Collective security falls within the competence of the United Nations, and individual States, as a rule, cannot act in the name of collective security.