On Nov. 1, a team of 35 experts carried out an exercise to inspect a simulated nuclear test site near the Dead Sea in Jordan. This was a step forward in completing the global verification system of the Comprehensive Nuclear-Test-Ban Treaty.

On Friday, the world’s Nobel Peace laureates will hold a summit in Hiroshima to stress the priority of nuclear disarmament and affirm their commitment to promoting it.

Countless other international initiatives are also underway that reflect a wider revolution in thinking about nuclear weapons — a revolution that is welcome and long overdue.

After all, despite much talk of nuclear disarmament when the Cold War ended 20 years ago, more than 20,000 of these weapons still exist, with many on high alert — and each much larger than the devices that devastated Hiroshima and Nagasaki in 1945. Nine countries are known or believed to possess them, and all are improving them in various ways.

The very existence of these weapons aggravates three global nuclear threats: from existing arsenals (accidents, miscalculations, unauthorized use or willful use), from their proliferation to additional states and from their acquisition by terrorists.

But now, a new global consensus is emerging that these weapons are militarily irrelevant in dealing with emerging threats, impossible to use without violating international humanitarian law, a source of proliferation and terrorist threats, and a waste of money and scientific talent.

This helps to explain why we are seeing new demands to start good-faith negotiations on nuclear disarmament, as has long been required by the Nuclear Non-Proliferation Treaty. United Nations Secretary-General Ban Ki-moon has made a persuasive case for work to begin on a nuclear-weapon convention or a framework of separate agreements resulting in a global ban.

Even the leaders of the nuclear-weapon states are now officially supporting the goal of global nuclear disarmament. They are joined by former statesmen, parliaments and regional organizations, mayors, retired military experts, women’s organizations, human rights activists, environmentalists and countless other groups worldwide.

Yes, nuclear disarmament has gone viral. It is now mainstream — a fitting subject for even die-hard realists to consider and no longer a cause promoted by peace groups alone.

We believe that this momentum is absolutely vital to international peace and security, and there are many ways to reinforce it. Achieving global nuclear disarmament will surely require new legal obligations for all states — nuclear and non-nuclear. To be blunt, the rule of law must be brought to disarmament. Commitments in this sensitive field must be made irreversible and subject to strict verification.

These tasks cannot be accomplished unilaterally. Multilateral cooperation is indispensable. Of course, some progress in treaty making by smaller groups of states is possible, particularly by those with the largest nuclear arsenals: Russia and the United States. Early ratification of the New START treaty would be a step in the right direction.

Yet other advances of the rule of law in nuclear disarmament will require cooperation on a global scale. One of the most important and overdue developments in this area is the entry into force of the Comprehensive Nuclear-Test-Ban Treaty, which will outlaw all nuclear explosions, regardless of their size, location or declared purpose.

The idea of outlawing such tests was first floated in 1954 by Indian Prime Minister Jawaharlal Nehru, who framed his proposal in the context of broader progress toward nuclear disarmament, just as we are doing today. The nuclear-test-ban treaty has now been signed by 182 states and will enter into force after being ratified by nine more: China, Egypt, India, Iran, Israel, North Korea, Pakistan and the United States, while Indonesia has announced that it will ratify it soon.

This ban on nuclear tests will be backed up with a verification regime that spans the globe. Even today, thanks to a variety of sophisticated means, we can detect very small nuclear tests in remote locations. The treaty is also fair because it includes the same rights and responsibilities for all its parties. It sets a new standard for nuclear weapons treaty obligations and verification.

The Comprehensive Nuclear-Test-Ban Treaty is needed because of the role of nuclear tests in the development and improvement of nuclear weapons. Such tests are also political symbols that have no place in a world determined to eliminate these abhorrent weapons of mass destruction. On an issue as important as this, voluntary promises not to test are simply not enough.

Other treaties are needed as well, especially one that outlaws the production of fissile materials for use in nuclear weapons. We believe that non-nuclear-weapon states also deserve legally binding assurances against the threat or use of nuclear weapons. Moreover, there is merit in seeking additional treaties to outlaw weapons in space, establish agreed-upon norms for missile defense and make certain that nuclear materials and technologies are kept safe and secure.

Together, these steps will take us far down the road to a world free of nuclear weapons — not as an act of faith, but as a prudent investment in the peace and security of all peoples. This would be perhaps the greatest legacy we could leave for future generations.