This book is organized in seven chapters. Chapter one looks at the origins and the causes of war. The chapter argues that war is a consequence of how we, as a species, have evolved. War has both endogenous and exogenous causes. While the former depends on our biology and psychology, the latter has to do primarily with international relations. Chapter two makes the case for the paradoxical nature of war. While war takes lives, it is legitimate under certain circumstances. For example, armed humanitarian interventions are allowed to save lives among local populations at the expense of the oppressors by employing all necessary means – ethical or not. Chapter three asks if peace among nations is achievable, which is the main theme of this book. However, it does not elaborate on the question entirely. Instead, it gives sort of a prelude of what will be discussed in the remaining of the book by talking about the concepts of world order and American hegemony, arms race, and peacebuilding. Chapter four builds on three by looking at realism, idealism, and pacifism in international relations. As to pacifism, the chapter attempts to answer the question, what was the most peaceful time in history? Chapter five presents the elements of hope for world peace by considering the role played by the following: (1) the United Nations; (2) the North Atlantic Treaty Organization (NATO); (3) the Organization for Security and Cooperation in Europe (OSCE); (4) the non-governmental organizations (NGOs); (5) the role of nuclear deterrence; (6) globalization; (7) transnationalism; (8) diplomacy; (9) sports; (10) international cooperation in space exploration; (11) the Nobel Prize; and (12) the declining of war and violence in modern times. On the other hand, chapter six presents the opposite argument or the barriers to world peace, using the following points: (1) the proliferation of nuclear weapons; (2) geoeconomics; (3) terrorism; (4) the global refugee crisis; (5) the profitability of arms sales; and (6) the profitability of wars. It makes an interesting argument especially as to the profitability of wars by showing how the United States, first, emerged as an imperial and a world power in the 1890s; then as the only world’s superpower after World War II. Finally, chapter seven takes a proactive approach by peering into the future of armed conflict, which is likely to take place in new environments: Cyberspace, the littoral, choke points, near space, and increasingly in expanding cities or slums War. The chapter concludes with a discussion on the Doomsday Clock, a concept stemmed from the uncertainty as to the future of mankind because of armed conflicts and which is a symbol that represents the likelihood of a man-made global catastrophe.