The 21st century is no different from any of the previous periods with regard to wars and conflicts. With only two decades down the lane, several regions have seen wars of different character: limited and all-out conventional wars, sub-conventional wars, blockades, externally sponsored internal revolts, and threats of nuclear posturing. The situation is alarming and calls for a serious review of the prevalent international order because the present international system, under the cloud of realism, has failed to avert wars and conflicts between rival states. This book argues that wars and conflicts become inevitable between archrivals with protracted conflicts if both diplomacy and deterrence fail to achieve their objectives. Furthermore, it explores the essential links between diplomacy and deterrence as essential tools to avert future wars, particularly between unequal military powers (UMPs).