NUCLEAR DETERRENCE 5 ved or disproved in an actual war, deterrence was tenous and more often than not broke down. It is only with the advent of nuclear weapons that the costs of aggression have skyrocketed. The mere existence of capability is not sufficient to ensure deterrence. For it to work, it must make any potential challenger believe that the costs of taking a prohibited action could exceed the gains to be made, but also that they would do so. Credibility is a complicated task and could vary from one situation to another. Credibility would depend significantly on the challenger's assessment of the deterrer's past political record, the strength of its political leadership, and how it could behave in a crisis. That is, if a challenger believes rightly oy wrongly, the leadership of the state undertaking deterrence is incapable of imposing unacceptable costs or it is weak and vacillating, det-terence is unlikely to work. A key condition for a successful deterrent strategy is that the potential opponent be made fully aware of precisely what range of actions is proscribed, and what would be the consequences if he oversteps the prohibited units. Clear communication is thus a necessity, but difficult to fully achieve in the politics of nation-states. Though a variety of communication channels exist between two adversaries, conveying an appropriate message or signal need-not be easy. Decision making in modern government is a highly complex and bureaucratic process, during which often contradictory 'signals' are likely to be conveyed to the adversary. The dangers of miscalculation are considerable in such situations. The reception, analysis and assessment of signals is itself a complicated organisational process. A signal by the time it reaches the adversarial leadership, could be completely distorted and easily be misunderstood by it. These conditions of deterrence are rarely satisfied in full measure in the real world of politics among nations. In the past, given the limited lethality, intensity and scope of warfare, the costs of failure of deterrence were not too high. But in the nuclear age, and in the era of global war, the consequences of failure of detterence would be cataclysmic. Before we examine the nature of nuclear deterrence, we must briefly review the two types of deterrence that existed in the pre-nuclear era. One is the passive deterrence, which seeks to dissuade an adversary from initiating war. Passive deterrence is an attempt to convince the opponent that he cannot be successful and denying him the objectives and goals he seeks. The second type, active deterrence, consists of readiness and capability to inflict unacceptable punishment and pain, in the event of deterrence failing. Historically, the use of the strategy of deterrence was predominantly at the level of denial. It is only with the advent of sea power and, later, air power, that the technological capacity to inflict heavy punishment, without first defeating the adversary's military forces came into being. Seapower enabled the disruption of vital seaborne trade routes, access to materials and markets and .thus impose heavy penalties over an aggressor. Air power, particularly the ideas of strategic bombing made deterrence credible, as it facilitated the bombing of civilian populations and adversary's warfighting capabilities. It