In today?s changing scenario, the key objective of national security is not only to protect the country from external aggression but also to maintain peace and harmony. To maintain law and order, peace and harmony, the Government should carry out the process of assimilation effectively without any delay and discrimination. However, the present situation in North East region of India is a logical culmination of negligence by the State as well as Central Government since independence of the country. With this perspective an attempt has been made to examine the internal security environment of Northeast region a long with geostrategic aspects and influence of external powers. The central theme of the book is to understand the insurgency of Northeast region in a comprehensive manner. The book mainly concentrates on the issue of Assam?s insurgency and counter-insurgency since 1985. The book also deals with various aspects of counter-insurgency policies formulated by the Central Government of India and State Government of Assam. The implications of insurgency and counter insurgency on India?s national security have been exclusively articulated by the author.