Though substantial progress has been made since the end of the Cold War in the dismantlement of US and Russian-held nuclear weapons, non-nuclear weapon states have become frustrated with the pace of disarmament. Two years ago, several states launched a new process that would delegitimize nuclear weapons by declaring a ban on their possession and use. Despite the objection of the nuclear weapon states and their allies, the UN General Assembly voted in late 2016 by a wide margin to begin negotiations on the text of a nuclear weapons ban treaty.

Though the movement is the product of laudable motives, the ban treaty is likely to have little influence on the nuclear powers’ strategic force-structure decisions, which are the product of a complex mix of strategic and political considerations. On the other hand, a variety of nonproliferation problems would be unaffected by the ban or even worsened. For example, the creation of an alternative treaty structure governing nuclear weapons could lead to “forum-shopping,” in which a state might hope to dilute international condemnation over its noncompliance with the strict verification requirements of the existing Nuclear Non-Proliferation Treaty (NPT) by participating in the new nuclear weapons ban treaty.

There is a relatively simple fix: Pro-ban states should insist that the new treaty contain an article reaffirming all participants’ obligations to the NPT. The article should include provisions that automatically rescind standing in the ban treaty should the International Atomic Energy Agency (IAEA) find a signatory to be noncompliant with its NPT obligations.

The ban treaty will remain controversial. It should not be controversial, though, to say that a treaty aspiring to a nuclear-free world should first do no harm to the existing tools we have to prevent the spread of nuclear materials and technology to new states, which are centered around the NPT.

Negotiations on the text. At this early date, with negotiations on the text yet to begin, little is known about the format or content of the nuclear weapons ban treaty. The drafters will have to resolve an underlying tension. A simple and largely rhetorical treaty would maximize the number of signatories, and avoid blowback from states that resist new legal obligations. At the same time, some states will want the treaty to demonstrate substantive progress. This could include any number of steps, ranging from directly strengthening nonproliferation norms and institutions to encouraging the International Court of Justice to reconsider its 1996 decision—which found that nuclear deterrence is legally permissible—on the grounds that the ban movement represents an evolution of international customary law and norms of behavior. The stated aims of the movement and a desire for a greater number of signatures suggest that a simpler text is more likely. In any event, the treaty is unlikely to provide for development of a framework for verifiable disarmament.

Nuclear weapon states have largely declined to participate in the ban process (though the United States, the United Kingdom, India, and Pakistan sent delegations to the ban movement’s final preparatory conference in Vienna in 2014). Concerned that confrontational rhetoric from some ban states signals a desire to achieve a treaty at any cost, the nuclear weapon states have expressed concern that the ban movement “may negatively affect the prospects for consensus at future NPT Review Conferences.” Observers in nuclear weapon states and elsewhere remain concerned that ban treaty negotiations could undermine the authority of NPT obligations, establish conflicting obligations, erode the effectiveness of the existing NPT system to resolve nonproliferation concerns, lead to a destabilizing counterreaction in nuclear weapon states, or distract attention from other critical priorities for nuclear governance and strategic stability.

Forum-shopping under a ban treaty. Treaty proponents have denied that their pursuit of a ban would distract from the broader nonproliferation agenda, noting that many ban states have supported the treaty precisely because they are committed to nonproliferation. However, their good intention is not sufficient to ensure the ban treaty’s complementarity with the existing NPT regime. If negotiators do not include specific provisions in support of the NPT, they could inadvertently do it substantial harm by creating an opportunity for nuclear aspirants to “forum-shop.”

This term, which has its origin in the legal profession, refers to an attempt by one party involved in litigation to find the most favorable jurisdiction in which to contest a case. In the present usage, we mean that a state might purposefully sign on to a simple ban treaty that lacks nonproliferation safeguards in order to avoid the more burdensome NPT requirements for international monitoring and transparency, which might allow them latitude to withdraw from the NPT.

Unless the text of the ban treaty explicitly forecloses this kind of behavior, a state that is party to both the NPT and the ban might perceive an additional opportunity: to withdraw from the NPT but mitigate some of the resulting political or military backlash by arguing that its membership in the ban treaty was sufficient to uphold its nonproliferation obligations. That state may appeal to other non-nuclear weapon states over unfair treatment under the NPT and argue that its fidelity to a looser, unenforced nuclear weapon ban treaty is sufficient to address international concerns about its activities.

Regardless of the reason that a state may choose to withdraw from the NPT, doing so would put at risk critical tools used daily to prevent the spread of nuclear weapons. Whether a state contemplates withdrawal to avoid IAEA inspections, to intimidate its neighbors, or (as some whispers warn) in protest against the pace of nuclear disarmament under NPT Article VI, the damage would be considerable. As a withdrawing state could not assure the international community that it was not seeking a nuclear weapon, suspicion could lead to an increased risk that nuclear powers intervene or neighboring states themselves proliferate.

Though the nuclear weapons ban treaty should act to prevent all states from forum-shopping, now and indefinitely, two cases are of particular concern in the near term.

The first is North Korea: Since the ascension of Kim Jong-un to power, North Korea has stopped trying to deflect attention from its nuclear program and has instead started to insist that the world recognize it as a normal nuclear power. The regime’s objective is to terminate the international effort to eliminate its arsenal, forever escape the possibility of IAEA inspectors on its territory, and successfully deter attacks by the United States and its allies. North Korea’s vote for the UN ban resolution suggests that it may attempt to participate in the new treaty negotiations. If it does, it may argue that it is interested in disarming like an established NPT nuclear weapon state rather than as an illegal proliferator, rendering IAEA safeguards inapplicable in the interim.

The other case of particular near-term concern is Iran. Even more than North Korea, it has sought to exploit international dissatisfaction with the United States and its nonproliferation policies to obstruct efforts to strengthen international safeguards and export-control standards. Iran has sought for years to augment its NPT obligations with a general statement of religious prohibition on nuclear weapons via a fatwa that Supreme Leader Khamenei allegedly promulgated in the 2006-2008 period. If the historic Iran nuclear agreement were to collapse in the coming years, it is not difficult to imagine a future Iranian government announcing that the combination of the fatwa and an international ban treaty provide all the necessary nonproliferation assurance the international community needs, and that it was justified in withdrawing from the NPT.

Nonproliferation enhancements to the nuclear weapons ban. Relatively simple additions to the ban treaty text would keep it from being used to cover NPT noncompliance or withdrawal. The easiest way would be for the ban treaty to include an article expressly designed to reaffirm and strengthen the commitment of all signatories to the NPT. A credible nonproliferation article will require at least three points.

First, the nuclear weapons ban treaty should require that all signatories be states that have ratified the NPT and are members in good standing. In practice, this would have the effect of prohibiting the participation of nuclear proliferators, including countries that never signed the NPT (India, Pakistan, and Israel) as well as those that withdrew from it (North Korea). This provision would serve as a firm statement that countries who are not committed to verifiable nonproliferation are not credible voices on the question of disarmament. It would represent a strong deterrent to states that are considering withdrawing from the NPT, ensuring that they cannot deflect international condemnation by claiming to be committed to disarmament proceedings via the ban treaty.

If negotiators believe this rule to be too restrictive, they might instead choose to require that all ban treaty signatories that were party to the NPT at the beginning of 2017 remain so in good standing. This weaker provision would deter withdrawal from the treaty but degrade its credibility on nonproliferation, by appearing to accommodate or, worse, rehabilitate North Korea. Still, it would be better than remaining silent on the question of NPT withdrawal: even with this formulation, treaty ban advocates would still be in a stronger position to deter noncompliance.

Second, the ban treaty should include specific language to clarify its relationship to the NPT, including:

A statement that no provision in the ban treaty in any way supersedes or alters the obligations of ban signatories, singly or collectively, to the NPT.

An explicit reaffirmation by all participants that they will continue to meet their NPT obligations, and an expectation that member states will expand compliance with existing nonproliferation regimes, including by implementing United Nations Security Council sanctions on North Korea, enforcing export control rules, and accepting rigorous Additional Protocol monitoring standards for their own facilities.

An avowal by all states party to the treaty that they will not support abuse of the NPT’s withdrawal provisions, and will impose costs on any state that withdraws on flimsy grounds, including by participating in multilateral sanctions regimes directed at that sate.

A renewed commitment to work to strengthen existing nonproliferation regimes, including export control standards and the provisions of the NPT itself.

National signature statements reflecting these commitments could also help amplify the message. Such statements would be especially valuable from states with a longstanding record of leadership in international nonproliferation efforts, like South Africa, Ireland, and Mexico.

Third, pro-ban states should support measures in nonproliferation institutions to register a consensus understanding that the ban does not absorb any of the vital functions of the NPT. The UN General Assembly’s First Committee ought to adopt a resolution coincident with the conclusion of ban treaty negotiations that outlines and clarifies the respective roles of the new treaty and the NPT. The IAEA Board of Governors should do the same, noting at the appropriate moment that there remains no substitute for the IAEA safeguards system, which should be strengthened.

The NPT system—and the arsenal of other tools it enables, through the IAEA and other organizations—is irreplaceable. A nuclear weapons ban treaty will have its best chance to promote a world free of nuclear weapons if it strengthens the NPT.