In the pre-nuclear age, the question of credibility in executing the threat was not a vital problem because the mighty side having the military means could carry out threat or launch an offensive while the weaker side was not allowed to take an aggressive action. Thus, the military means and the willingness were two foremost factors requisite to fulfilling the threat whereas after nuclear revolution, the deterrence theory speaks predominantly about the credibility. In literary sense, ‘deterrence means to prevent people from doing something by frightening them, particularly through threats of severe consequences.’ Later, the concept of nuclear retaliation further consolidated the threat by permitting vigorous punishment without allowing realistic defence, because after the introduction of nuclear or strategic weapons, the cost of nuclear weapons is no more restricted to the battlefield or front line and the nation’s infrastructure, population and industries cannot remain intact in modern conflict. The general realisation is that in a nuclear conflict, either side would lose more than it gains. Thomas Schelling argues that in nuclear coercion, actors can credibly threaten or take steps on the route that may eventually result in the situation getting out of control. The destruction done by nuclear weapons was first witnessed by the world in the Second World War when Hiroshima and Nagasaki were hit by the atomic bomb. The general perception is that since the advent of the nuclear weapons, the sense about major world war has grown. The potential impact and efficacy of nuclear weapons spurred a debate between proliferation optimists, the more the better, and pessimist, more will be worse. It is yet to be seen whether North Korea will be deterred from developing nuclear weapons by threat of destruction or through by a mix of incentives, disincentives and sanctions. The cost of failed deterrence will be immense On the notion of deterrence, optimist argue that the nuclear proliferation decreases the likelihood of war. Kenneth Waltz opined that nuclear weapons can increase stability among states because due to deterrent factor and nuclear retaliation, the states will tend to avoid war; both conventional and nuclear. Whereas, the nuclear pessimists argue that states possessing nuclear weapons may not necessarily come in mutually deterring pairs or stable relationships which would increase the risk of accidental nuclear war. Pessimist also contend about the possibility of preemptive strike between two hostile states possessing nuclear weapons and sharing common borders although deterrence till now worked in such cases, for instance between US-USSR, Soviet Union-China, India-China and Pakistan-India. The cold war model is the most recounted to explain this phenomenon as the hostility between United States and Soviet Union did not escalate into direct military conflict despite the height of tensions. On the contrary, with reference to ongoing US-North Korea tensions, the US President’s national security adviser HR McMaster, in an interview, disagreed with the perception that “US and its allies will tolerate nuclear weapons in North Korea and rely on traditional deterrence to prevent the North from using them, just as they had deterred the Soviet Union from using its much more massive nuclear arsenal during the Cold War”. However, there are other Trump advisers who think that deterrence can work with North Korea. On the other hand, Pyongyang claim to complete the miniaturisation of hydrogen bomb capable of being fitted to an intercontinental ballistic missile is also important component of the North Korea’s deterrent strategy. The country is showcasing its capabilities to demonstrate that it can cause significant damage to adversary. Thus, the derivatives of deterrence are certainly functional in current tensions. Yet a noticeable fact or limitation is that even if deterrence can stop a state to launch an aggressive action, it cannot prevent a country to further develop nuclear weapons. Nonetheless, if North Korea is not deterred, then it will go on and make nuclear weapons which can be one of the most dangerous weapons in the world. Robert Gallucci, a former Clinton administration official, rightly questioned that “what makes deterrence unreliable in North Koreans case as it is certainly not the quality or quantity of North Korea’s nuclear weapons because Soviet Union had about thousands of weapons at height of Cold War while North Korea have less than 20”. The United States have so far deterred governments in past from using nuclear weapons that include Joseph Stalin in the Soviet Union and Mao Zedong in China. However, whether North Korea would be deterred by destruction or change its calculus on the development of nuclear weapons by the incentives, disincentives or sanctions is yet to be seen but the cost of failed deterrence is unimaginable. The writer is a Senior Research Associate at an Islamabad-based think tank, Strategic Vision Institute (SVI). She works on issues related to nuclear non-proliferation, arms control and South Asian nuclear equation. She writes for South Asian Voices, international blogs and national dailies. She can be reached at firstname.lastname@example.org Published in Daily Times, September 26th 2017.