Living in a world with nuclear weapons means living, however uncomfortably, with a certain degree of uncertainty. Nuclear weapons make widespread destruction on an unfathomable scale seem almost instantaneous. Popular culture reinforces the message: with the push of a button, the world might be engulfed in a sea of mushroom clouds. On more than a few occasions, what saved the planet from devastating strikes boiled down to little more than luck.

To harness the destructive power of nuclear weapons, planners throughout the Cold War tried to impose a degree of logic. They organised, armed, and then threatened to unleash nuclear strikes on adversaries, seeing nuclear deterrence as the most effective way to keep the peace. It was a posture often justified as the best (or least-worst) of the options available to ensure that Europe did not end up plunged into great-power war for the third time in a century.

Deterrence rests on a series of uncomfortable assumptions, starting with what would happen if nuclear weapons ended up deployed in conflict again. Coming to terms with that risk plagued NATO’s strategy over the years. The alliance’s European members understandably chafed at anything that suggested deterrence might break down and war break out. After all, during the Cold War, that war would be fought on their territory.

But these anxieties often ran up against the realities of crafting a strategy fit for the nuclear age. To make deterrence credible, the architects of NATO’s strategy designed and fielded new weapons systems in the hopes of convincing allies and adversaries that deterrence would hold. And yet, in considering how these might be used, the Americans seemed all too willing to entertain so-called ‘war-fighting’ uses for these missiles beyond the strict roles envisioned in deterrence in which the Europeans hoped these weapons would be never fired.

NATO’s strategy after 1967, a loose doctrine of escalation known as flexible response, left these two schools largely intact. They coexisted uneasily in the same strategy, as the Western allies concluded that a degree of ambiguity would be necessary to keep everyone on side. The end result was an alliance with no clear sense of how flexible response would work in practice or, for that matter, if it would work at all. But however nebulous, flexible response had staying power. For all its flaws, it still seemed preferable to the alternatives.

That did not mean there was an easy case for an allied strategy reliant on the firepower of nuclear weapons. When non-specialists stopped to dwell on the subject, they often found little to like about NATO’s planning. Such were the difficulties of reassurance. Policies and procurement programmes designed to reassure allied governments about the depth of the US commitment to Europe’s defence could all too easily leave those same governments’ citizens terrified that the very weapons designed to protect them would put them at greater risk.

Take, for instance, the Dual-Track Decision that NATO’s members adopted in December 1979. The contours of the decision were simple enough: a parallel scheme to deploy new missiles in Western Europe, slated to be hosted in Belgium, the Federal Republic of Germany, Italy, the Netherlands, and the United Kingdom after 1983, and to negotiate with the Soviet Union to limit nuclear weapons with a similar range, including the Soviets’ new SS-20 missiles. The Dual-Track Decision marked the end of years of internal wrangling as the Western allies tried to shore up NATO’s deterrence strategy, and members’ confidence therein. But it quickly came under fire as voters across the Atlantic alliance worried the decision would make nuclear war more likely, not less.

That sense of fear drove record numbers into the streets in the early 1980s, armed with placards and posters denouncing NATO’s planned deployments and the dangers of nuclear weapons. Half a million people descended on Amsterdam in October 1981 in a turnout so large that a planned march through the Dutch city could not take place; the streets were too packed for anyone to move. That same scene played out in cities and towns across the alliance. When protestors gathered in New York City in June 1982, the crowd was so big police struggled to estimate how many people were there, putting the numbers somewhere between 600,000 and 700,000.

These demonstrations brought together a diverse cohort opposed to NATO’s Dual-Track Decision for a variety of reasons. There were old hands of the movement to ban the bomb, and newcomers worried about the dismal state of US-Soviet relations. Some took issue with the economic costs of the arms race, while others rejected the logic that more nuclear weapons would somehow make them safer. Among their ranks were some spurred to action by the financial support and well-placed messaging of the Warsaw Pact’s members, though the degree of communist influence was nowhere near as total as some contemporaries suggested. Even the CIA admitted as much. ‘Despite these unceasing efforts by the Soviets and their local allies, we believe that Communist infiltration, funding, and influence are secondary factors in the West European peace movement,’ one assessment concluded. ‘Strong anti-nuclear movements probably would have developed in all of the INF [intermediate-range nuclear force] basing countries (except Italy, where the determining influence of the powerful Communist Party is ambiguous) even without Soviet or Communist involvement.’

One popular line of rhetorical attack in the streets zeroed in on the risky business of deterrence. Religious groups debated the morality of a strategy that relied on threatening violence, split on whether benefits outweighed risks. Other pockets of opposition focused their attention on what would happen if deterrence failed. Based on the capabilities of NATO’s new weapons, the ground-launched cruise missiles and Pershing IIs, some observers concluded the alliance had abandoned deterrence in favour of a war-fighting posture.

Even if NATO’s plans remained reliant on deterrence, was that a desirable or comforting outcome? The prominent British historian and peace activist E.P. Thompson dismissed superficial assumptions that deterrence worked. ‘Very possibly it may have worked, at this or that moment, in preventing recourse to war,’ he wrote in 1980’s Protest and Survive. ‘But in its very mode of working, and in its “postures,” it has brought on a series of consequences within its host societies.’

Similar scepticism could be found far outside activist circles. The early 1980s saw a sprawling debate about the nature of nuclear deterrence. Academics and defence analysts returned to old ideas about how to reduce dependence on nuclear weapons by strengthening conventional deterrence. NATO continued to make the case that nuclear deterrence remained the backbone of Western security, but it was clear even some of the alliance’s most powerful political leaders questioned the wisdom of relying on nuclear weapons. Despite hawkish rhetoric that left some listeners rattled, the sitting US president, Ronald Reagan, envisioned a world without nuclear weapons. It was an impulse visible in repeated calls for arms reductions (not the sky-high caps imposed by earlier agreements with the Soviet Union) and his enthusiasm for the Strategic Defense Initiative as a way to break out of the nuclear straitjacket. ‘He was just antinuclear,’ one former Reagan adviser, Kenneth Adelman, concluded.

The fragile foundations holding up nuclear deterrence continued to fracture as the 1980s wore on. NATO’s contentious deployments began in 1983, as cruise missiles and Pershing IIs began arriving in the Federal Republic of Germany, Italy, and the United Kingdom, but the fundamental debate about nuclear weapons remained. What role could they play in allied strategy? What role should they play? These questions came to a head once more when it increasingly seemed possible that the United States might be able to reach an arms control deal with the Soviet Union. It was all the more alarming that an agreement might be based on the Reagan administration’s original negotiating position, the so-called zero option which would do away with all US and Soviet medium-range missiles.

When confronted with the possibility that the zero option might form the basis for an agreement, earlier endorsements gave way to panic. Any such treaty would remove an entire class of nuclear weapons in Europe and beyond. It would undercut NATO’s standing strategy, reliant as it was on the promise — or threat, depending on one’s vantage point — of escalation. The prospect terrified British Prime Minister Margaret Thatcher. It was all too easy to imagine how removing one class of missiles might ratchet up the pressure, pushing NATO to abandon a strategy built around nuclear weapons. She remained all the more vigilant against these risks after Reagan joined with Soviet General Secretary Mikhail Gorbachev to sign December 1987’s Intermediate-Range Nuclear Forces Treaty, abolishing every land-based missile with a range of between 500 and 5,500 kilometres.

Thatcher described nuclear weapons as the sole area of meaningful disagreement between her and Reagan. Where the president contemplated the abolition of nuclear weapons, Thatcher kept the faith that only deterrence made sense. ‘It is a world which I cannot foresee existing,’ Thatcher remarked to an interviewer in 1990, ‘because there have always been evil people in the world, they will always be born and there are always going to be and you have to consider the worst thing. You have to consider something so terrible that you can say to him: “You will never get away with this and so you do not start it!”’