Far from being relics of the past, atomic bombs must be managed as the embodiments of human-made catastrophe that they are

Nuclear-weapons risks are back — and we need to act like it

Far from being relics of the past, atomic bombs must be managed as the embodiments of human-made catastrophe that they are

At a time of growing catastrophic risks posed by climate change, pandemics and advances in artificial intelligence (AI), and more than 30 years after the end of the cold war, many people consider nuclear weapons to be relics of the twentieth century. Eighty years into the nuclear age, which began in 1945 with the first test — called Trinity — of an atomic weapon in the New Mexico desert, and the bombings of the Japanese cities of Hiroshima and Nagasaki, these devastating weapons have, fortunately, never since been used in war.

But amid a rise in geopolitical rivalries, technological advancements and civic discord, the shadow cast by nuclear weapons over international politics is growing once again. It is also manifesting in unprecedented ways, as the past few months show starkly.

In May, intense, albeit brief, fighting broke out between two nuclear-armed rivals when India and Pakistan traded air strikes, missile attacks and more; the scope of the violence was unprecedented between two nuclear-armed states. In June, Russia became the first nuclear-armed state to lose a significant number of nuclear-capable platforms after Ukraine carried out a daring attack, using drones to destroy bombers on Russian soil.

Less than two weeks later, Israel, an undeclared nuclear-armed nation, carried out the most ambitious military action to stem nuclear proliferation in history, striking at Iranian nuclear facilities. Iran’s retaliation with hundreds of missiles constituted the largest-ever attack against the heartland of a country possessing nuclear weapons.

The conversation around nuclear weapons has also shifted. From East Asia to Europe, allies of the United States are asking whether they can continue to rely on its guarantees of nuclear deterrence or might need a plan B, possibly involving nuclear weapons of their own. South Koreans are watching with trepidation as North Korea’s nuclear arsenal grows in number and sophistication. Meanwhile, eastern European members of the North Atlantic Treaty Organization are concerned as Russian nuclear weapons enter Belarus, and Moscow’s reliance on its own nuclear capabilities to project power seems to grow.

Although non-nuclear states are unlikely to sprint to the bomb any time soon, loose talk around the pursuit of nuclear weapons speaks to growing malaise about a world that is more primed for conventional wars and about a less consistent United States, as well as to the reduced unease about the prospect of nuclear war.

Relations between China, the United States and Russia encapsulate this dynamic. China, for reasons that remain uncertain, has embarked on an ambitious build-up of its nuclear arsenal, which, US intelligence suggests, could go from roughly 200 warheads in 2019 to 1,500 by 2035. Meanwhile, Washington and Moscow will soon find themselves unburdened by numerical limits on their nuclear forces for the first time since the 1970s, when the 2011 Strategic Arms Reduction Treaty, or New START, expires in February 2026.

Unnerved by increased competition with both of these nuclear-armed rivals, the United States is likely to deploy more nuclear weapons on its existing submarines and intercontinental ballistic missiles, while pursuing an ambitious approach to missile defence in what has been dubbed Golden Dome. A three-way arms race is all but certain to ensue. Governments and scientists need to be prepared for the consequences.

Trends are reversing

The global outlook was very different back in 1991 when the cold war ended, giving way to a period of broader global optimism about the part that nuclear weapons would play in world politics. Coinciding with the Soviet Union’s collapse, both Washington and Moscow withdrew thousands of nuclear weapons that they had deployed abroad (see ‘Global nuclear-warhead inventory’).

Source: The Bulletin of the Atomic Scientists’ Nuclear Notebook (**go.nature.com/4JQYHWT**)

In the years that followed, both the United States and Russia made sharp reductions in their strategic nuclear weapons — those that could hit the other’s territory — acknowledging a transformed security environment. Arsenals numbering in the tens of thousands in the 1980s were reduced by an order of magnitude by the following decade. Still, nuclear weapons and their risks didn’t evaporate: crises in South Asia and the Korean Peninsula have persisted. But the oppressive shadow of nuclear Armageddon involving the United States and the Soviet Union receded.

During the 1990s, there were significant efforts to universalize international norms against the spread, and testing, of nuclear weapons: the 1970 Treaty on the Non-proliferation of Nuclear Weapons was extended indefinitely in 1995, and, the following year, a Comprehensive Nuclear Test Ban Treaty was opened for signature. The goal of global nuclear disarmament seemed viable for the first time.

Yet, today, even as trend lines head in the opposite direction, members of the public around the world are paying little heed. They are aware of nuclear weapons but have largely not yet grasped that the risks these represent are multiplying.

For the past 30 years, the relatively benign post-cold-war nuclear environment has allowed global attention to turn elsewhere: to the liberalization of trade, the pursuit of multilateralism and sustainable development, and counterterrorism after the 11 September 2001 attacks in the United States, for example.

For those who came of age in this calmer world, nuclear weapons are something seen in films set in the cold war, or referenced in works of music from previous eras. By contrast, for those who lived through the cold war, almost everyone — whether citizen or soldier or politician — needed to know at least a little about nuclear weapons. By the 1980s, such knowledge and fear of nuclear war had permeated so deeply that large protests against the bomb proliferated. Today, people need to reacquire that literacy.