The book deals with the aspect of pre-emptive use of force under International Law as a measure of self-defense. The value of the topic has been revived in the backdrop of the escalating tensions due to the inevitable withdrawal of the armed forces from Afghanistan, the recent territorial attacks on the Pakistan soil under the Doctrine of Hot Pursuit (against non-state actor/s), and the interventions in Libya, Egypt, especially the on-going crisis in Syria. The book incorporates the entire history, concepts and doctrine and succinctly puts them in a chronological order all in one location, tempting the readers to read the entire enigma. It extensively draws out the lacunae in the existing UN Charter and provides the possible solutions through the Model Amendment Code annexed as Appendix I. The content and language of the book is such, that it makes it an indispensable resource for students, academicians and practitioners and acquaint any law undergraduate or post graduate to the nuances of Use of Force and self-defense under the International Law of Armed Conflict.