Until very recently, the prospect of nuclear weapons use by a major nuclear power has appeared relatively remote, enabling other issues—terrorism, climate change, Covid—to dominate the global agenda. But that period of relative immunity to Armageddon has drawn to a close and we have entered a New Nuclear Era, in which the risk of nuclear weapons use by the major powers has reemerged as a daily fact of life. We may yet escape their use and the resulting human catastrophe, but only if we oppose the nuclearization of world affairs with the same vigor and determination as has been devoted to overcoming the climate crisis.

During the Cold War, of course, the threat of nuclear weapons use was ever present. Any major clash between the superpowers—say, over Berlin or Cuba—was assumed to harbor a potential for rapid escalation from non-nuclear, “conventional” conflict to nuclear war. After the cuban missile crisis of 1962, in which a nuclear conflagration was barely avoided, the United States and the Soviet Union tried to avoid actions that might lead to a direct clash between them, but both continued to enhance the destructive potential of their respective thermonuclear arsenals. Only with the end of the Cold War and the dissolution of the Soviet Union did the threat of instant annihilation cease being a constant global worry.

In the years following the Cold War, the prospect of a nuclear exchange between the major powers largely disappeared from the agendas of international policy-makers. That does not mean that the danger of nuclear weapons use disappeared entirely: Both the United States and Russia engaged in the continuous modernization of their atomic arsenals; China, India, Israel, and Pakistan expanded their stockpiles; and the US and North Korea exchanged some harsh nuclear threats. But few outside of the military and a small specialist community paid much attention to these developments and the persistent dread of nuclear annihilation—so widespread during the Cold War era—largely evaporated.

With Russia’s invasion of Ukraine, however, all that has changed. We have now entered a period in which the deliberate use of nuclear weapons is again a distinct possibility, and every clash between the major powers carries the risk of nuclear escalation.

The conditions that made this transformation possible—including a renewed emphasis on nuclear war-fighting among the major powers—have been in place for several years, but the decisive shift was propelled by Russian President Vladimir Putin’s multiple threats to employ nuclear weapons against any other state that attempt to impede his drive to subjugate Ukraine.