National security is a collective term that encompasses several dimensions starting from military advantage of a nation state over others to its survival through various means like arms race, diplomacy, economic power and many other forms of soft power. It is the highest order of protection of a nation state from external dangers as well as internal. Therefore, national security challenges can be broadly divided into two categories, domestic and external. The external security aspect cannot be delinked from domestic security. The term national security as a concept developed mostly in the United States in the post-World War-II scenario. The conventional definition of national security relied mostly on realist interpretation and it defines the term mainly from the military prospective. The international politics was considered to be a war game and it was a sort of maximization of power by the states through war, arms race etc. The non-conventional security threats and non-state actors remained missing in academic discourses and policy formulation. However, such sole focus on military might of a nation state started changing with the paradigm shifts in many spheres of geo-politics, economy, technology and culture after the World War-II. Since then, the concept of national security started including many other dimensions like energy security, environment security, food security, human security, economic security and more recently cyber security. The security threats are changing and there is an increased trend of limited and hybrid wars in the world politics.