When have nuclear weapons come closest to destabilising world peace – and how close to the brink of nuclear war did the world come?

Benoît Pelopidas: “How close was it?” is a misleading question if asked alone. One also needs to ask: how controllable was it? Indeed, some proponents of nuclear deterrence claim that you need to get close enough to the ‘nuclear abyss’ for the deterrent effect to kick in. But is that true? And can we control how close we get? A critical moment commonly cited in this regard was the Cuban Missile Crisis of 1962. And that was not fully controllable: the caution of Soviet premier Khrushchev and US president Kennedy alone cannot explain its peaceful outcome, given the limits of their control over their nuclear arsenals, the limits of safety of the weapons, and other factors. The evidence shows we have been lucky. Though the scholarly and policy worlds pay lip service to this finding, they still do not act and plan as if they take it seriously.


Secrecy means that we know very little about cases of near use of nuclear weapons. It’s very likely we overestimate how safe we have been.

Malcolm Craig: There are a number of other examples of times when this has happened. For example, during the first year of the Korean War (1950–53), President Harry Truman’s bluster and outbursts from General Douglas MacArthur provoked international fears about perceived American willingness to use atomic weapons.

Perhaps the most interesting example was the November 1983 Able Archer incident , in which a Nato communications exercise was perceived by some in Moscow as preparation for an actual offensive. In this case, nuclear weapons, paranoia and faulty intelligence-gathering could have (a big ‘could have’) led to nuclear war.

Simon J Moody: In my judgement, the closest nuclear weapons have come to destabilising world peace was during the first decade of the Cold War, from the late 1940s, when the United States had nuclear superiority. If decision-makers had heeded the arguments for nuclear release – to support outnumbered UN forces during the Korean War, or to help relieve the beleaguered French garrison at Dien Bien Phu in Vietnam in 1954 – then today’s situation, in which the non-use of nuclear weapons is seen as normal, might never have been established. It is the taboo nature of nuclear weapons use that helps to stabilise weapons of such appalling power within an anarchic international system.

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The panel

Malcolm Craig is senior lecturer in American history at Liverpool John Moores University, specialising in post-1945 US and UK foreign policy

Michael Goodman is professor of intelligence and international affairs in the department of war studies at King’s College London

Simon J Moody is lecturer in defence studies at King’s College London, specialising in the history of strategic thought

Benoît Pelopidas is professor, junior chair of excellence in security studies, and scientific director of the masters programme in international security at Sciences Po (Paris)

Conversely, how important a factor have nuclear weapons been in preserving world peace, and how have they done so?

BP: If you mean how important a factor have nuclear weapons been in preventing a great power conflict or nuclear war, deterrence theory claims that the destructive capability of nuclear weapons triggers fear, which in turn makes leaders cautious. However, recent scholarship shows that this relationship is far from automatic; classic works have also shown that threats intended to deter may have adverse effects, as can any other public policy. If one needs to constantly establish the credibility of a deterrent threat based on nuclear weapons, this will obviously lead to more risk-taking. The question then is: what are the other effects of nuclear weapons in the world beyond security issues? How do nuclear weapons programmes affect the governments and states that build them?

MC: Returning to the Cuban Missile Crisis, though nuclear weapons were a fundamental part of why it occurred, they also played a major role in bringing it to a peaceful conclusion. The thought of global nuclear war caused both leaders to pull back from the brink and achieve a negotiated solution.

Michael Goodman: A certain view of proliferation holds that peace is best achieved through a parity in weapons – in other words, the best means of ensuring peace has been for both sides of a conflict to have a nuclear capability. There is certainly some credence to this: just consider two big nuclear-tipped conflicts or confrontations – the Cold War and India-Pakistan tensions. Arguably, the fear of either a nuclear pre-emptive strike, or the guarantee of Mutually Assured Destruction (MAD), has been enough to ensure that in those scenarios (relative) peace has been preserved.

What other factors have been more important in maintaining peace?

BP: Given that nuclear war or nuclear weapons use would be unacceptable by most constituencies, factors that have been necessary to prevent nuclear weapons use even once are crucial. We now know that in 1961, two 4-megaton thermonuclear weapons fell from a US B-52 plane over Goldsboro, North Carolina; the only thing that prevented one of these weapons from exploding was a safety switch that remained in the safe position. However, that switch malfunctioned several times in other instances. So the only thing that prevented a 4-megaton nuclear detonation on that day was the random non-simultaneity of the failure of the plane and that of the switch. There is no other name for this than luck. Beyond that, the notion of deterrence, which describes the intended effect of a policy, gives the impression that this intended effect is an actual effect. And nuclear weapons discourse has created the impression that deterrence in terms of war prevention can be achieved only with nuclear weapons. Once those discursive effects are undone, the other factors in maintaining peace reappear, including the absence of desire to attack, and sensitivity to the security dilemma of the other.

MC: Two factors (there are many others) are the destructiveness of major 20th-century wars, and luck. Even before the atomic age, there was considerable international concern that major interstate wars were becoming so destructive as to be untenable. The First and, most significantly, Second World Wars proved this point.

Returning to Cuba, luck – in the sense of the right person making the right decision at the right time – played a significant role in global nuclear war being averted. Soviet submarine officer Vasili Arkhipov could have agreed to the firing of a nuclear torpedo at US warships. US fighter pilots could have launched nuclear-tipped rockets at their Soviet counterparts. Sometimes, luck really is a factor.

MG: One of the great Cold War lessons was that it was not enough to have a nuclear capability – it was just as important to have knowledge and understanding of your adversary’s arsenal. The key lay with intelligence: gauging your opponent’s political intentions and military capabilities was tremendously important. With the exception of the Cuban Missile and Able Archer crises, at no point did the intelligence service of one side predict the other was about to launch a pre-emptive nuclear strike – and even in these two cases it was a political concern rather than an intelligence one that led to the worry. In other words, maintaining a nuclear arsenal to react, and an offensive intelligence agency to monitor, were part and parcel of maintaining peace.

SJM: International organisations such as the UN have played an important role in the maintenance of world peace. Although critics have questioned the effectiveness of bodies such as the Security Council to enforce its resolutions, in lieu of a world policeman the UN continues to legitimise the actions of its members and is probably the best structure we have for maintaining basic human rights. In addition, most forms of political, economic and cultural integration help to maintain the international order. The EU, for example, emerged out of various postwar experiments to regulate the industrial economies of western Europe, and has thus rendered the prospect of war between European nations economically illogical and politically absurd.

How important is the balance of nuclear weapons between different powers?

BP: The two major military powers of the Cold War (the US and Soviet Union) were the first two to develop nuclear weapons, building 70,000 of them. That suggests that, at least for a time, possession of nuclear weapons in large numbers was a crucial feature of world power. However, those two countries possessed many other features of power. Also, Japan, Germany, South Korea and South Africa have explicitly built their strategy of emergence on the international stage on renunciation of nuclear weapons.

Members of groups such as the G7 to G20 [representatives from the banks and governments of the world’s leading economic nations] have increasingly included non-nuclear-armed states, and emerging states have rarely sought to acquire those weapons. It’s notable that India failed to acquire the status of permanent member of the UN Security Council after its nuclear weapons tests. Nuclear-weapon states have been attacked and lost wars against non-nuclear-weapon states (the US in Vietnam, for example, and the Soviet Union in Afghanistan). So nuclear superiority has not been sufficient to guarantee either victory or war prevention. The record of coercion based on nuclear superiority is very limited. During the Cuban Missile Crisis, nuclear weapons use was avoided through luck. In that crucial case, nuclear balance was simply irrelevant.

MC: As with any historical issue, contingency and context are all. Up to the launch of Sputnik in 1957, the Soviet Union could not – in any meaningful sense – wage nuclear warfare against the US. In that case, the number of weapons mattered less than the ability to deliver them.

By the 1970s, both sides had massive arsenals based on missile technologies that could target anywhere in the world. At that point, the number and sophistication of weapons mattered, in a very general sense.

But in some cases, nuclear capability matters not a jot. British governments have been heavily invested in the idea of a nuclear weapon state, but do those weapons deter potential enemies? Britain’s nuclear status did little to deter Argentina in 1982. Likewise, Al-Qaeda wasn’t deterred by the vast US nuclear arsenal. This leads to another question: what purpose do nuclear weapons serve in the 21st century?

MG: The science and technology of nuclear weapons is such that a vast array of constructions is possible. These range from early atomic devices tested in the 1940s and 1950s (and replicated to an extent by the early devices of most nuclear states), to the advanced and fantastically destructive thermonuclear weapons of the 1950s and onwards. Yet as the explosive yield has varied, so too has the means of delivery: the early devices were dropped from planes, with delivery then progressing to missiles and the miniaturisation of the so-called suitcase bomb . Accompanying this technological change is the sheer scale of nuclear arsenals – yet there comes a point, defined as ‘nuclear sufficiency’ by the British Ministry of Defence in the 1950s, when your opponent has enough weapons to produce any variable of these. At that point, size no longer matters because your destruction is guaranteed.

SJM: The relative balance of nuclear power is essential to the logic of strategic nuclear deterrence. The security paradigm of the Cold War remained so stable because of the paradox of Mutually Assured Destruction – the state whereby opposing nuclear powers each possess the means to launch a decisive nuclear attack against the other, even after absorbing a first nuclear strike itself. By threatening to unleash on a decisive scale the very process it seeks to avoid – war – MAD ensures that the consequences of a strategic nuclear exchange are sufficiently terrifying to convince a would-be aggressor that the costs of war outweigh the benefits.

Has the aspiration of non-nuclear powers to gain nuclear weapons been a destabilising factor around the world?

BP: The spread of nuclear weapons is dangerous. It increases the risk of nuclear detonations, either deliberate or accidental, by state and possibly non-state actors. But, once again, to fully answer your question one would need to know what the development of nuclear weapons programmes does to the governance of a polity. A research programme addressing this very issue is starting.

The assumption of the inevitability of a desire to acquire nuclear weapons has also been very destabilising. It has justified non-proliferation policies, including violent ones, neglecting the fact that most states never had any interest in developing such weapons, and that, among the few who did, most gave up before crossing the nuclear threshold.

In other words, giving up nuclear weapons ambitions is not only the result of an absence of capabilities (think Sweden), the presence of the weapons of a protector (think South Africa) or the success of the use of force (think Iraq in the 1980s or Libya after 1986). Ignoring or denying the clear reasoning for such non-nuclear security strategies may embolden those who argue nuclear weapons are necessary or helpful for maintaining security.

MC: One of the remarkable things about nuclear proliferation is that, despite consistently alarmist assessments of ‘tipping points’ and ‘cascades’, few countries have chosen to attain full nuclear capability. Nations such as Argentina, Sweden and South Korea all had at least partial nuclear programmes at some point since the 1950s, but chose to abandon their ambitions. There were many reasons: internal politics, outside influence, leaders’ psychology, and so on. In some ways this tells us that the reasons not to go for full nuclearisation are more popular than the reasons to do so.

However, nuclear weapons are an issue in the tension between India and Pakistan. Pakistan has ‘the bomb’ as a fundamental part of its strategy in the event of major war with India. Any potential battlefield use of tactical nuclear weapons could escalate a conflict to the strategic nuclear scale, with horrific regional and global consequences.

SJM: Nuclear proliferation is not inherently destabilising, and there is a logical argument, rooted in deterrence theory, that the emergence of more nuclear states might in fact bring greater stability to certain regions. India and Pakistan are both new nuclear states and, though some form of limited military conflict between the two rivals is a distinct possibility, the risks of a costly and unrestricted conventional conflict has largely been nullified by the presence of nuclear armouries.

Likewise, Israel is another example: though its status as a nuclear power has not been officially declared, the possibility of such states acquiring nuclear weapons might have reduced the existential threat of invasion by one or more of its openly hostile neighbours.

MG: Nuclear weapons are essentially an asymmetric tactic of choice: a single bomb offers a means of offsetting the balance of power. For large powers this is arguably less of an issue; for smaller powers it allows them to punch above their weight and compete with larger powers whose conventional armies dwarf their own. For this reason, a nuclear capability, regardless of its inherent difficulties and associated costs, is an attractive option for medium and small-sized powers. In these sorts of scenarios, just one power in a region or conflict is likely to have a nuclear device, so the possibility of destabilisation is far greater. For this reason the proliferation activities of the Pakistani nuclear scientist AQ Khan took on a great significance, because he sold blueprints and technical equipment to aspiring states including Iran, North Korea and Libya – with very real and frightening consequences.

Do you think that nuclear weapons will ensure world peace in the future?

MG: In a word: no. The deterrent effect of possession of a nuclear weapon is obvious and with historical precedent, but that does not mean that irrational leaders won’t consider using them either pre-emptively or for a specific purpose.

While warfare increasingly moves towards the cyber domain and non-kinetic electronic or other remote technological] means, nuclear weapons remain the diametric opposite. They are the red line that no state has crossed since August 1945, but this lack of use is not enough of an argument to say that they have ensured world peace. They are a tactic of last resort, but peace will be pursued separate to nuclear weapons. That said, they are an important and valuable commodity to any defensive arsenal, so will remain a significant factor in world politics for the foreseeable future.

SJM: As a historian, I would naturally be reluctant to peer too deep into the future.

What the historical record tells us, however, is that the security framework within which nuclear weapons have become so ingrained is remarkably stable, and that total war (as our grandfathers’ and great-grandfathers’ generations twice knew it), really does seem to be a relic of the industrial age. Yet nuclear weapons are not a panacea for ensuring world peace, as demonstrated by the proliferation of conventional conflicts since 1945. Real world peace rests on the ability of humans to solve their political differences through understanding, compassion and co-operation.

BP: Since the beginning of the nuclear age, nuclear weapons were not designed to preventall forms of violence, and have not done so. The extent to which they have been central to the prevention of war between major powers since 1945 is also contested. They primarily generated a vulnerability, from the moment when undetectable submarine-launched ballistic missiles made it impossible to defend against a nuclear attack. Nuclear-weapon states have been attacked and lost wars against non-nuclear-weapon states, and actors willing to give their life for a cause may not fear nuclear retaliation. This is as true as it ever was.

As scholars and citizens, we have a responsibility in building the future. Perpetuating overconfidence in the controllability and safety of nuclear weapons allows for complacency. It neglects the role of luck and failures in avoiding nuclear weapons use in the past. Beyond the security dimension, the question of the future of nuclear weapons raises ethical and political issues about what kind of political communities we want to be in the eyes of future generations – and what we want to leave them.

In context

The Cuban Missile Crisis

Following the failed CIA-backed Bay of Pigs invasion of Cuba in 1961, Fidel Castro made a secret agreement with Soviet premier Nikita Khrushchev to install strategic nuclear weapons on the island. Much of the US would then be within effective range of Soviet nuclear missiles.

On 14 October 1962, an American U-2 spyplane captured photos indicating the presence of ballistic missiles in western Cuba – in contravention of promises made by Khrushchev to US president John F Kennedy. The US responded by establishing a naval ‘quarantine’, blocking the delivery of further offensive weapons. Khrushchev called this action “outright piracy”, warning that it could lead to war.

Tensions rose over the following two weeks. Both US and Soviet nuclear forces were readied, and Castro’s communications with Khrushchev seemed to urge a Soviet nuclear strike on the US in the event of another invasion of Cuba. A number of incidents could have sparked the launch of nuclear weapons – most notably when the US Navy dropped depth charges on Soviet submarine B-59 near Cuba; a retaliatory strike with nuclear torpedoes was vetoed by only one submarine officer, Vasili Arkhipov. Secret exchanges between Kennedy and Khrushchev finally resulted in an agreement on 28 October: the US would remove its Jupiter missiles from Italy and Turkey (from where the Soviet Union was in range), and in return the Soviets would remove their offensive weapons from Cuba. Nuclear war – which seemed possible or even likely – had been averted.

Able Archer 83 incident

A Nato exercise simulating a conflict escalation, codenamed Able Archer, was conducted in western Europe in November 1983. Fearing that the exercise might be a ruse to mask an actual nuclear strike, the Soviet Union readied its forces in preparation for retaliatory nuclear action – a very real threat that, thankfully, receded at the end of the exercise.

Dien Bien Phu

Site of the decisive battle in the First Indochina War. Defeat of French forces by nationalist-communist Viet Minh troops on 7 May 1954 augured the end of nearly a century of colonial rule in Vietnam. The US had supplied materiel to the French, but plans to deploy US nuclear weapons against the Viet Minh were not enacted.


The launch of the first artificial satellite, Sputnik 1, by the Soviet Union on 4 October 1957 signalled the start of the ‘space race’ between the US and USSR. The R-7 rocket that took Sputnik into orbit was originally developed to carry a nuclear warhead.

Suitcase bomb

Prototype nuclear weapons of portable size and weight were designed by both the United States and Soviet Union during the 1950s and 1960s. However, it is still uncertain whether actual production of effective suitcase bombs (light enough to carry but with sufficient destructive yield) was successful.

AQ Khan

Abdul Qadeer Khan is a Pakistani nuclear physicist who in the 1970s headed a uranium enrichment programme for his country’s atomic bomb project. In 2004 it was revealed that Khan had sold nuclear technology to states including Iran, North Korea and Libya.


This article first appeared in issue 6 of BBC World Histories