Article 51 of the UN Charter

Article 51 of the UN Charter recognizes that countries have the right to defend themselves if they are attacked. It allows a nation to use force to protect itself until the UN Security Council can take action to maintain peace and security. Importantly, any self-defense must be necessary and proportionate to the attack, and countries are expected to notify the Security Council promptly. This article balances a nation's right to self-defense with the international effort to prevent conflict through multilateral cooperation.