To what extent do the rights of anticipatory and pre-emptive self-defense exist under international law

Self-defense has been historically recognized as a legitimate action by the international community and is said to be inherent in the concept of Statehood. Traditional concept of war e.g. State v State war has mostly been changed – and nowadays, especially after the event of 9/11 in the United States – States are fighting to defend themselves against the non-State actors – an unseen enemy, which has essentially raised questions on the extent of right of Self-defense of a nation-State. Because, the existing international law – the Caroline Doctrine, Article 51 of the United Nations Charter and Security Council Resolutions – does not provide sufficiently clear guidelines regarding when a State may take anticipatory or pre-emptive action against a State or a non-State actor. After examining international law, this article proposes a proper understanding of the nature of the right of Self-defense and most pertinently, the possible existence of right of anticipatory and pre-emptive Self-defense in existing international law.