This volume draws attention to new uncertainties and challenges that have emerged in India`s security environment in the last few years because of the volatile nature of international relations. The 21st century has witnessed the evolution of relations among nations in a manner that has disrupted the sanctity of the international order built in the 20th century. For instance, the rule-based international system is being violated and the violators are not being punished. There is a tendency on the part of major powers to pursue policies governed by nationalism and protectionism without caring for their impact on other nations. The legitimacy of international agreements has been diluted by abrupt withdrawal of big powers from them. The rise of China as an economic and military power and its assertiveness has ruffled the international environment, making choices difficult for smaller nations. The resurgence of Russia and its unquestioned aggressive behaviour vis-a-vis other nations has established a new norm. The proclamation of “America First” doctrine by Donald trump has cut into the very spirit of “collective security” which was the basis of United Nations. It is in this kind of disruptive environment that India has to safeguard its national security against the onslaughts of its adversaries and the shifting behaviour of its partners and neighbours. Despite India`s best efforts to improve relations with China, the future is uncertain. India`s surgical strikes across the LoC on 29 September 2016 and its retaliatory air strike on Balakot terrorist training camp on 26 February 2019 have led us nowhere to believe that Pakistan will be deterred. Despite United States and India having moved closer to each other in defence cooperation, how far United States will stand by its commitments in times of crises remains a question mark. Russia is an old and tested friend but its closeness with China in recent years and its newfound fascination for Pakistan have created a dent in the Indian mind in its trustworthiness. As far as India`s neighbours are concerned, they have been always regarded as reliable partners in India`s security architecture. But whether geopolitical changes brought about by China`s desire to intrude into India`s strategic space in South Asia will allow the neighbours to remain trustworthy partners is a new challenge that India faces. These and other aspects of India`s security environment in the context of a highly unstable international situation have been thoroughly examined.