Challenges to Nuclear Deterrence

Since 1945, there has been no war with nuclear weapons, and there has been no direct conflict between two major powers in possession of nuclear weapons. To proponents of nuclear deterrence, these two facts may offer a compelling case, because according to them, nuclear weapons have made war among great powers too expensive.

Nuclear pessimists, on the other hand, imply that nuclear deterrence may be a tool to avert a nuclear war, but it cannot guarantee that a state will never use a nuclear weapon during a crisis, a concern shaped by the dynamics of war in South Asia and the Russia-Ukraine war. That is, the argument is enticing, but the inference is faulty: the absence of an event is not proof that it was prevented.

Building on a debate on nuclear deterrence and its success, Bruno Tertrais contends that other theories of sustaining peace, including economic interdependence, democratic norms or institutions, are less compelling than the logic of mutual destruction.

Extended deterrence has also been argued to effectively constrain other powers in Europe and East Asia from developing their own armaments. Based on this reasoning, nuclear weapons have limited proliferation as well as war.

The challenge is to deal with the other half of the debate. One can only test nuclear deterrence by its failure, and failure would be catastrophic. Nuclear history between the Soviet Union and the US reflects episodes where deterrence came close to weakening.

The Cuban Missile Crisis of 1962 is often cited as an example of how diplomacy and luck helped manage the crisis between the Cold War nuclear rivals. 

In 1983, a Soviet officer’s decision to distrust a false satellite alarm may have averted a launch. In fact, as Scott Sagan argues in his book on organizational behavior, nuclear-armed states are operated by fallible institutions; accidents, misunderstandings, and routine procedures can all affect the rationality of the calculation on which deterrence theory rests.

This is to say that surviving seventy years without a major catastrophe is not the same as having a safe system. It may just mean that the dice have rolled in our favour until now.

Compared with the West, South Asia is a harder test than the Cold War ever was. As both India and Pakistan possess nuclear weapons, a full-fledged war becomes unimaginable, while limited aggression at the sub-conventional level becomes more tempting as escalation is deemed controlled.

The Kargil conflict in 1999, the stand-off in 2001-02, the crisis in 2019, and the conflict in May 2025 are no exceptions. Each crisis brought the world closer to the precipice, but nuclear deterrence prevented a general war each time; it did not, however, prevent crises.

When flight times are short, and the delivery systems are two-in-one, leaders have only a few minutes to read and interpret mixed messages. Emerging technologies are even compressing the decision time for possible retaliatory responses. 

However, not all scholars share this pessimism. A realist perspective of nuclear optimists suggests that nuclear deterrence works because other options are too costly to contemplate. As early as 1946, Bernard Brodie proposed that the bomb had transformed the use of military force from victory in war to the prevention of war.

Thomas Schelling demonstrated that the risk of mutual destruction, in part random, can rule out the conduct of opponents. Kenneth Waltz took it one step further, arguing that nuclear arms generate caution and that proliferation can even calm the relations between rivals. Robert Jervis talked of a “nuclear revolution” in which assured retaliation makes great-power war irrational, and John Mearsheimer believed nuclear weapons would make the risk of major war less. 

Thus, an equitable conclusion may be provisional. Nuclear deterrence seems to have succeeded in one thing: it has deterred direct and deliberate war between the nuclear-armed states. However, many presume it may be less effective in coercion, proxy warfare, grey-zone aggression, or crises of miscalculation. These may not be deterred through nuclear deterrence, but they can surely play a role in bringing two nuclear-armed states to the verge of an all-out war.  To avert that, a system of restraint is crucial.

Besides, these emerging challenges may require other related strategic elements at the sub-conventional level, such as terrorism, proxies, non-state actors, disruptive technologies, etc. The success of such a system requires perfect rationality, precise interpretation and good fortune, and these three must continue indefinitely, because if it doesn’t succeed, its consequences cannot be undone.

What would be more useful, therefore, is the question of what would make deterrence stability work in the longer run. Several measures can be drawn. Opponents should establish, test, and protect communication routes during a crisis from political conflict.

Arms control negotiations should resume with the principal powers and expand to include new technologies. The reliance on AI and cyber in nuclear command and control requires deliberate restraint; that is, short time spans and miscalculated steps are the best accelerators for unintended escalation.

Existing confidence-building measures in South Asia, including the 1988 agreement on nuclear facilities and the 1999 Lahore Memorandum and the missile test notification arrangement, may be enhanced instead of being left to expire.

Nuclear deterrence has proven to be effective; though there is no evidence of its failure, it has bought time. For it to become a trustworthy system of restraint, it must be maintained through continuous, up-to-date measures.