Perhaps for the first time, the nuclear-weapon states are really afraid. Not because of their enemies’ nuclear weapons, let alone their own, but because of the likely start of multilateral negotiations for a nuclear-weapons ban. The odds are good that nuclear weapons will be declared illegal in the foreseeable future.

In fact, it is surprising that nuclear weapons are not yet declared illegal, just as chemical and biological weapons are. The Nuclear Non-Proliferation Treaty (NPT), the cornerstone of the nuclear nonproliferation and disarmament regime, only forbids the possession of nuclear weapons. The five nuclear-weapon states that acquired nuclear weapons before the entry into force of the NPT—the United States, Russia, the UK, France and China—were allowed to keep them. At the same time, they pledged to get rid of them. The problem is that this promise dates back to 1970 and there are still fifteen thousand nuclear weapons in the world, endangering every state, not just the few nuclear-weapon states.

Because of the relatively slow rate of nuclear reductions, and the stalemate of classic multilateral diplomacy like the UN Conference on Disarmament and the repeated failures of the NPT Review Conferences, a group of middle powers and NGOs (especially the International Red Cross and ICAN) launched the so-called Humanitarian Initiative. The goal of the Humanitarian Initiative is to change the existing narrative of nuclear deterrence, nuclear proliferation and more recently nuclear terrorism to the question of the humanitarian consequences that will ensue, for societies and individual human beings, if nuclear weapons are ever used again.

Over the last several years the Humanitarian Initiative has been successful in stirring up multilateral nuclear diplomacy: three international conferences were organized in 2013 and 2014, with an increasing number of states attending, and there is growing support at NPT “Prepcoms” and NPT Review Conferences, as well as at the UN General Assembly First Committee. Around 150 states have either supported the so-called Humanitarian Pledge (which was previously called the Austrian Pledge) or the UNGA First Committee resolution that resembles it. The pledge aims “to identify and pursue effective measures to fill the legal gap for the prohibition and elimination of nuclear weapons.” In fact, most states in the world apart from the nuclear-weapon states and their allies have at least implicitly expressed their support for starting a process that will lead to a nuclear-weapons ban, something that was still regarded as utopian as recently as ten years ago. In 2016, the diplomatic focus will be on the UN Open-Ended Working Group, where the same issues will be discussed.

The Humanitarian Initiative has sparked new interest in nuclear disarmament within global civil society, including within the younger generation and in continents (like Africa) that were previously less involved in nuclear disarmament. The signing of a nuclear-weapons ban will empower civil society worldwide even more, accumulating the momentum required to tackle other challenges, such as climate change.

There are two major misunderstandings about the prospect of a nuclear-weapons ban. The first is about the scope of the treaty; the second is on the need for having the nuclear-weapon states on board. Some believe that a nuclear-weapons ban means the abolition of nuclear weapons. Others think that a hypothetical Nuclear-Weapons Ban Treaty would be the same thing as a treaty outlining the steps needed to abolish all nuclear weapons. Both are wrong. A Nuclear-Weapons Ban Treaty is a relatively minor step in the process of getting rid of nuclear weapons. The text of a Nuclear-Weapons Ban Treaty can and would be relatively short. The major goal of the treaty is to outlaw nuclear weapons, just as other weapons categories have been declared illegal before. To abolish nuclear weapons thereafter, two additional and more complicated steps are needed: first a Nuclear Weapons Convention (NWC), similar to the Biological Weapons Convention of 1972 and the Chemical Weapons Convention of 1993. A NWC will outline the steps that are required to reach zero nuclear weapons worldwide, including a far-reaching verification and sanctions regime. The second and last step towards zero consists of all states’ implementation of the NWC, including all nuclear-weapon states. As long as some nuclear-weapon states object to the principles and timelines outlined in the NWC, a world without nuclear weapons will remain a pipe dream.

However, in comparison with the negotiation and implementation of a NWC, the negotiation of a nuclear-weapons ban is a piece of cake. Negotiating a multilateral nuclear-weapons ban, in fact, resembles the logic of the step-by-step approach that the nuclear-weapon states and their allies generally favor.

This brings us to the nuclear-weapon states’ allies. While it is perfectly understandable that the nuclear-weapon states do not favor a ban on nuclear weapons, this position does not hold for their allies. The latest NATO Strategic Concept, from 2010, no longer explicitly states that nuclear weapons are fundamental for the alliance’s security. Nevertheless, the non-nuclear-weapon states that are allied with a nuclear-weapon state (including all NATO member states, as well as Japan, South Korea and Australia) find themselves in a very awkward position. At first sight, they will have to choose between their membership in a nuclear alliance and their commitment to a world free of nuclear weapons. On the other hand, NATO's Strategic Concept includes the goal of a world without nuclear weapons and promises further nuclear-arms reductions. Being a member of NATO and signing up for a Nuclear-Weapons Ban Treaty is therefore not incompatible. It is not because NATO has stated that as long as there are nuclear weapons NATO will remain a nuclear alliance that individual member states cannot actively cooperate in helping to bring about a world without nuclear weapons. The Washington Treaty does not even mention nuclear weapons.

In practice, nuclear burden sharing within the alliance has always been unequal. Some NATO member states, like Iceland and Lithuania, have always refused to station nuclear weapons on their territories; others, like Denmark, Norway and Spain, only in times of peace. Some have even shown an active interest in getting rid of nuclear weapons in the world. Norway, for instance, organized the first Humanitarian Initiative conference. Norway, Denmark and Iceland have often voted in favor of resolutions advocating the humanitarian approach. Indeed, these states are not only member of a collective defense organization (NATO), but they are also part of a collective security organization (the UN) and are signatories of the NPT. Indeed, a Nuclear-Weapons Ban Treaty is not in contradiction to the NPT; rather, they are complementary. And of course, all member states of an alliance retain individual sovereignty. That applies both to the nuclear-weapon states (the United States, the UK and France) that may want to cling to their nuclear weapons, and to the non-nuclear-weapon states that want to delegitimize nuclear weapons.

The second point of confusion about the Nuclear-Weapons Ban Treaty is that many observers believe that a nuclear-weapons ban without the nuclear-weapon states makes no sense. That belief is false. Of course, the participation of the nuclear-weapon states—the five official ones as well as India, Pakistan, Israel and North Korea—is required to get eliminate nuclear weapons. They will have to be involved in negotiating the Nuclear Weapons Convention. As stated before, at this stage we are not talking about a Nuclear Weapons Convention, only about a nuclear-weapons ban. These two are fundamentally different treaties, and they must be implemented in a specific order: first the Ban Treaty, and thereafter the NWC. Advocates of a ban are fully aware that the nuclear-weapon states are not yet ready to negotiate, let alone sign, a nuclear-weapons ban. They are also aware that the non-nuclear-weapon states are currently unable to convince the nuclear-weapon states to get rid of nuclear weapons. The nuclear policy of the nuclear-weapon states can only be altered by pressure from within these states. But as ideas float freely, especially in a globalized world, outside pressure may help to increase domestic constituents against nuclear weapons within the nuclear-weapon states.

Enter the Nuclear-Weapons Ban Treaty. The major goal of a Ban Treaty would be to elevate the nuclear taboo to prominence and, by doing so, stigmatize the spread of nuclear weapons. The hope is that by doing so a societal and political debate will arise, including in some of the (democratic) nuclear-weapon states.

If just one nuclear-weapon state changes its status, as South Africa did in the past, and becomes a non-nuclear weapon state as a result of that debate, the advocates of the Ban Treaty will have met their goal. This would, in turn, have a substantial positive effect on the worldwide nuclear nonproliferation and disarmament regime. It will put much more pressure on the other nuclear-weapon states to follow; it is always easier to follow than to lead.

The most likely candidate that might come under a lot of pressure to give up its nuclear weapons is the UK, where there has always been an active peace movement—in contrast, for instance, to France. Current Labour leader Jeremy Corbyn (who now enjoys a higher job-approval rating than David Cameron) is a lifelong member of the Campaign for Nuclear Disarmament, and made disarmament one of his major election themes. Despite union criticism, there is no sign that he will weaken his point of view. Corbyn has already stated that if he becomes prime minister, he will “never push the button,” and he proposed to replace the nuclear weapons in British submarines with conventional weapons. The Scottish Nationalist Party (SNP) is also very outspoken against nuclear weapons, and made gains in the latest election partly on the basis of the nuclear-weapons issue; additionally, the SNP has been effective in changing Scottish Labour members' point of view. Apart from the Greens, who are by definition against nuclear weapons, the Liberal Democrats are no enthusiastic advocates of Trident either. The result is that in the UK today, only the Conservatives are still in favor of a full-blown renewal of Trident. With increased financial pressure on the defense budget, and Cameron hampered by the Panama Papers, debate in the UK is open.