The Nuclear Weapons Ban Treaty: An expert’s legal analysis

At our recently completed 26th Annual National Security Law Conference, we were honored to have Ms. Alexandra Perina, the Assistant Legal Adviser for Nonproliferation and Arms Control at the U.S. Department of State, give us a legal analysis of the Treaty on the Prohibition of Nuclear Weapons (TPNW).

Among other things, she explains why the U.S. (and other nuclear powers) are not a party to it, even as the U.S. remains committed to nuclear disarmament. She also points out the issues the TPNW raises in relation to the Nuclear Non-Proliferation Treaty (NPT) to which the U.S. is a party.

(Some of my own views about the TPNW are found in this post “John Stuart Mill and the Treaty on the Prohibition of Nuclear Weapons” which links you to a longer essay -“Is the Treaty Banning Nuclear Weapons Immoral?”- over on War on the Rocks.)

Ms. Perina provides us with a wonderfully nuanced dissection of the TPNW with a keen eye towards implications not readinly discernable from the text.  Here’s a very lightly-edited transcript of her presentation (and the headings are my adds):

The Nuclear Weapons Ban Treaty: A Legal Analysis

Thank you for having me. I certainly wish we could be together in North Carolina right now, but it’s a pleasure to be with you virtually this afternoon to discuss the ban treaty, or formally, the Treaty on the Prohibition of Nuclear Weapons, which in my head is reduced to the acronym TPNW so I may refer to it as that in these remarks.

US commitment to nuclear disarmament

President Biden and Secretary Blinken have both made clear that the United States has not just a national security imperative, but also a moral responsibility to reduce and eventually eliminate the threat posed by weapons of mass destruction.

The United States has long supported the goal of nuclear disarmament, and indeed has undertaken in the Nuclear Non-proliferation Treaty, the NPT, the obligation to pursue negotiations on effective measures toward that end. We see that as an incremental process. Progress on which depends largely on the prevailing security environment and which cannot occur in a vacuum.

And that’s really exactly why we don’t support and won’t join the ban treaty. In fact, no state known or believed to possess nuclear weapons does support the ban treaty. Nor does any state, in fact, that relies on nuclear deterrence by a treaty ally. So, why not? I’ll discuss today some of the legal concerns and risks with the ban treaty from the US perspective.

I know there’s a range of backgrounds in the audience today. So I wanted to spend just a few minutes to set the stage with a brief overview of what the TPNW actually contains and then place it in the broader context of disarmament efforts.

Against that backdrop I’ll talk about why the United States opposes the treaty and views it not just as an ineffective measure in advancing disarmament, but also as potentially harmful to the existing non-proliferation and disarmament architecture under which genuine progress could be made.

By way of background, the TPNW was negotiated at a conference convened in 2017 pursuant to a UN General Assembly Resolution, and the text was finalized in a matter of mere weeks in that summer. It opened for signature in September 2017 and it has now entered into force as of January 22nd of this year, which was 90 days after the deposit of the 50th instrument of ratification or accession.

As mentioned, none of the nuclear weapons states under the NPT, the United States, UK, France, Russia, and China, or any of the states known or believed to possess nuclear weapons, participated in those negotiations.

So what does the treaty prohibit? It prohibits all parties from developing, testing, producing, otherwise acquiring or possessing nuclear weapons or other nuclear explosive devices, from using or threatening to use nuclear weapons, from transferring or receiving nuclear weapons, including control of such weapons, from allowing the stationing or deployment of nuclear weapons in the territory or under the jurisdiction or control of a state party. It also prohibits parties from assisting, encouraging, or inducing anyone to engage in activity that’s prohibited under the treaty.

The treaty, of course, allows for states without nuclear weapons to join. But it also permits states that still have nuclear weapons to join prior to eliminating their nuclear weapons, notwithstanding all of the prohibitions that I just mentioned, many of which are obviously incompatible with possession of nuclear weapons.

With respect to safeguards and verification, the treaty’s requirements differ depending on the status of the state party. So it defers all significant disarmament negotiation, disarmament verification requirements, for resolution in the future with undefined terms and through undefined mechanisms. And I’ll come back to that later.

The treaty requires state parties to take appropriate national measures, including penal sanctions to prevent and suppress activity prohibited by the treaty. And it includes provisions that require assistance to victims of nuclear testing and environmental remediation. It also includes, I’ll just note, a withdrawal provision that requires states’ parties to give 12 months notice of withdrawal. And it provides that withdrawing parties must remain bound, even after that 12-month period, for so long as the state is a party to an armed conflict.

Key concerns

What are the key concerns with the TPNW? Well, first, it purports to position itself within the NPT framework. It refers to the NPT and the preamble as the cornerstone of the non-proliferation and disarmament regime, although it misstates the NPT’s obligation on disarmament. But, in fact, it dispenses with some of the key balances that make the NPT work. So, for example, a central policy criticism of the TPNW is that it doesn’t take into account the international security environment in which disarmament must occur.

Whereas, the NPT recognizes that, quote, “the easing of international tension and the strengthening of trust between states”, end quote, would facilitate disarmament, the TPNW doesn’t acknowledge or reflect that relationship. The NPT nuclear weapon states have made clear that complete disarmament in the current security environment is simply unrealistic, and that progress on disarmament is necessarily tied to improvements in international security which requires a more gradual approach that builds on successes.

Moreover, the NPT rests upon three pillars– non-proliferation, disarmament, and the promotion of peaceful uses of nuclear energy. But the TPNW fails to acknowledge the critical interrelationships between these three objectives. The NPT recognizes, quote, “the inalienable right of all the parties to the treaty to develop research, production, and use of nuclear energy for peaceful purposes without discrimination and”, this is the important part, “in conformity with”, which is therefore conditioned on, “their non-proliferation obligations.”

Treaty omits the link to non-proliferation obligations

The TPNW in its preamble emphasizes the same right to develop nuclear energy for peaceful purposes, but omits the link to non-proliferation obligations. Similarly, TPNW seeks to advance disarmament without commensurate progress on non-proliferation.

And in particular, it adopts the non-proliferation safeguards standard of the 1970s and overlooks the critical efforts to strengthen those safeguards with new standards that began in the ’90s. Instead, it prioritizes progress on disarmament at the expense of non-proliferation in a way that, I’ll turn to now, could distort and undermine the existing non-proliferation framework.

With respect to non-proliferation verification under the treaty, as mentioned earlier, the non-proliferation safeguards required by the TPNW vary depending on the status of the state party. So for those states’ parties that did not have nuclear weapons as of July 2017, it sets out two possibilities.

The first is that those without existing safeguards agreements must enter into, at a minimum, the comprehensive safeguards agreement with the IAEA, which is the current standard required under the NPT, to assure the non-diversion of nuclear material from peaceful purposes to weapons.

The other possibility is that those states that have existing safeguards agreements in place with the IAEA must maintain those safeguards. And this would require those states that have concluded an additional protocol to the CSA, which is aimed at verifying the absence of undeclared nuclear material and activity, to maintain the AP as well. So this sets out a differentiated and static standard between non-nuclear weapon states that have adopted the AP already and those that have not.

This was a political compromise during the TPNW negotiations designed to accommodate key TPNW proponents that don’t have APs. And importantly, it could undermine the safeguards standards in the NPT which is widely viewed to be evolving and for which a combination of the AP, the CSA, and the AP is already widely recognized as the de facto standard. The TPNW sets out yet a different requirement for any state party that had nuclear weapons as of July 2017.

Such a state would be required to have safeguards, quote, “sufficient to provide credible assurance of the non-diversion of declared nuclear material from peaceful nuclear activities and of the absence of undeclared nuclear material activities in the state as a whole.” That’s an indirect reference to both the combination of the CSA and the AP, the Comprehensive Safeguards Agreement and the Additional Protocol.

Differentiated requirements

So perhaps, most concerningly, the overall result of the TPNW’s differentiated requirements is that a state like Iran, which is a nuclear weapons state under the NPT and does not have an additional protocol in force, although it has been applying it provisionally, would be required under the TPNW to accept a lower standard of non-proliferation safeguards only a comprehensive safeguards agreement or CSA then the United States would if the US were to accede to the TPNW.

That kind of stratification seems almost certain to lead to mistrust amongst these parties by leaving open the possibility for precisely those states that have been reluctant to adopt the AP to date to pursue clandestine nuclear programs with a lower likelihood of detection.

Treaty’s disarmament verification approach ill-suited to realities

With respect to disarmament verification, the TPNW’s approach seems equally ill-suited to the realities that nuclear weapon possessor states considering disarmament would face. So to begin with, the TPNW deferred the challenging issues of how to effect and verify disarmament in favor of fairly vague and broad requirements.

Under the TPNW, a state party that possesses nuclear weapons must immediately remove those weapons from operational status and submit a plan for the verified and irreversible elimination of such weapons within 60 days. This plan, which would be legally binding and time bound, would be negotiated with a, quote, “competent international authority” that is yet to be identified and designated under the treaty. The plan would then be submitted to other states’ parties for approval.

So in other words, the ban treaty seems to contemplate that states possessing nuclear weapons would join the treaty with the details of disarmament including verification to be worked out later. Its provisions offer, at best, a sort of notional roadmap rather than a detailed system for disarmament and verification.

And it’s simply hard to imagine that any nuclear weapon possessor state would agree to join the treaty without the details of such undertakings being carefully negotiated and settled in advance. The meeting of states’ parties, would be empowered to make decisions about these matters under its rules of procedure that do not necessarily guarantee exceeding nuclear weapons possessors the ability to protect their national security interests.

And it’s worth noting that the verification of disarmament is really no small task. One example that’s often given is that of the New START Treaty. The New START Treaty contains 10 lines of text that set forth its central limits and then 356 pages of detailed text addressing a verification system that make those reductions achievable.

A disarmament plan and verification apparatus for an entire nuclear arsenal is a tremendous undertaking and one that would require extensive negotiation of separate instruments, and would need to address, also, the concerns of nuclear weapon possessor states that disarmament verification activities would not themselves become an avenue for proliferation.

So given the obligation of nuclear weapon states’ parties to the NPT not to assist any non-nuclear weapons state acquire a nuclear weapon, there would be serious questions about who would be competent to verify such disarmament, and whether the TPNW is to be designated competent international authority, whoever that may ultimately be, rather than other NPT nuclear weapon states would be in a position to do that kind of verification.

In sum, the ill-defined approach to disarmament in the treaty departs so fundamentally from the key arms control and verification practices that have been developed through painstaking negotiation in current and previous arms control agreements that it’s really difficult to imagine that any state possessing nuclear weapons would rely on the TPNW as the basis for its own nuclear disarmament.

Potential to undermine the NPT

I wanted to make one last point about the NPT which is that the TPNW could undermine the NPT insofar as it could expressly supersede it where there may be conflicting obligations. Although, as I mentioned, the TPNW pays lip service to the NPT as the cornerstone of the non-proliferation and disarmament regime. Article 18 of the TPNW provides that in the event of a conflict between the TPNW and a preexisting treaty, like the NPT, the TPNW would prevail for states that are party to both treaties.

Although, the TPNW obviously can’t affect the rights and the obligations owed under the NPT to state to their NPT parties alone, it could lead to interpretive conflict. And so the United States has completely rejected the idea of subordinating the NPT to the TPNW, and notes that to the extent there were to be a conflict, article 18 of the TPNW could not and does not affect the obligations owed by a TPNW state party to an NPT state party that has not joined the TPNW.

Treaty’s basic obligations incompatible with nuclear deterrence including mutual defense alliances

There are some potential implications for other legal relationships outside of the NPT framework that TPNW could have impacts in other areas, especially since its basic obligations seem to be incompatible with nuclear deterrence including mutual defense alliances, such as NATO. So as noted earlier, the TPNW prohibits states’ parties from using or threatening to use nuclear weapons and from assisting, encouraging, or inducing a state from engaging in such conduct.

These obligations taken together would appear to preclude a state party from participating in a defense alliance that’s predicated on nuclear deterrence. The TPNW also prohibits the state party from allowing any stationing, installation, or deployment of nuclear weapons on its territory or under its control that would prohibit nuclear basing arrangements. And notably, again, no non-nuclear weapon state that participates in a defense alliance backed by nuclear deterrence provided by a nuclear armed state has supported or joined the TPNW.

Other adverse impacts

In addition, some TPNW states’ parties have already indicated that they interpret the prohibition in the treaty on aid inducement and encouragement to preclude even transit or overflight of nuclear weapons through their territory under their jurisdiction. That’s despite the fact that an express prohibition on transit was considered and rejected during TPNW negotiations.

Given that it’s US policy, neither to confirm nor deny the presence of nuclear weapons at any specific location, including on US ships or aircraft, measures adopting such an interpretation could have broad implications for US military activities.

The vague and disputed scope of these prohibitions also raise questions about whether defense cooperation by TPNW states’ parties with non-nuclear weapon states that are under a nuclear umbrella could be viewed as prohibited as well. For example, could a TPNW state party export equipment for use by the armed forces of a state allied with a nuclear armed state? Or would such engagement be potentially viewed as encouragement of or assistance to activities prohibited under the treaty?

It’s worth pointing out that these prohibitions on transfer or control of nuclear weapons when combined with the broad prohibition on providing or receiving assistance to such activities would also appear to preclude a TPNW state party from assisting in the removal of nuclear weapons from other states. So this has been a critical role that NPT nuclear weapon states are able to fulfill consistent with their NPT obligations.

If, for example, the NPT nuclear weapon states were to join the TPNW, the treaty’s provisions would appear to not only impede, for example, efforts to denuclearize North Korea but also prevent them from either providing or receiving assistance in a crisis situation involving terrorism and a nuclear weapon.

Problematic implementation measures

In terms of implications for private citizens and entities, the TPNW requires its states’ parties to take, quote, “appropriate national measures to prevent and suppress activity prohibited under the treaty undertaken by persons or on its territory under its jurisdiction or control.” So how states’ parties implement this provision will be something to watch closely because it could entail significant risks for individuals and private entities, as well, such as banks that work with NPT nuclear weapons states and their allies.

Similar provisions requiring national implementation measures in other treaties, like the Ottawa Treaty banning landmines and the Convention on Cluster Munitions, suggests that this provision could be widely interpreted to require measures prohibiting and sanctioning financing of activities prohibited under the treaty.

The United States would urge TPNW states’ parties and any state considering becoming a TPNW party to consider really carefully the implications of the scope of any national measures that they adopt, including the possibility that such measures will have even broader impacts than might be intended if other states and private entities sort of de-risk by limiting their engagement with such states.

Customary international law?

And finally, I wanted to make one last point about customary international law. There have been a number of other legal criticisms and questions about the TPNW, but the last one I want to just raise on these remarks relates to the relationship between the treaty and customary international law.

There have been efforts to promote the treaty as contributing to the development of a new rule of customary international law that prohibits the possession of nuclear weapons, perhaps, seeking to bind nuclear weapon possessor states indirectly in recognition of the fact that they appear not to be joining the treaty itself.

The United States has firmly rejected any claim that the TPNW reflects or could contribute to the development of such a customary norm. It’s simply unsupportable, really, under international law. Although, that doesn’t mean it won’t create sort of confusing and distracting arguments.

To just explain this a little further, customary international law is evidenced with two features. First, the general and consistent practice of states, including specially affected states. And second, opinio juris, or the belief that the practice is required by an existing rule of law. In the case of nuclear weapons possession, of course, none of these elements exist.

In practice, states do possess nuclear weapons, and those states would be considered to be specially affected. They do so largely subject to treaty regimes like the NPT that recognize such possession. And any prohibitions on nuclear weapons possession are expressly treaty based like in the NPT or in nuclear weapon free countries, rather than reflecting a widespread customary international law.

Moreover, the TPNW itself is inconsistent with the creation of a norm of non-possession of nuclear weapons insofar as it doesn’t actually prohibit states from joining the treaty while they still have nuclear weapons.

Instead, it contemplates that such states would relinquish their nuclear weapons at an unspecified future date under unspecified future circumstances. And so it should be no surprise that the NPT nuclear weapon states and their military allies around the world have consistently and openly opposed the idea that the TPNW advances in any way customary international law.

Concluding observations

In closing, I would say that it could be easy to be cynical about the nuclear weapons states rejection of the ban treaty and try to suggest that it reflects a lack of commitment to disarmament. But a closer look at the TPNW, I think, reveals that it’s simply ineffective in advancing its cause because its prohibitions are vague and broad and present these questions about how its implementation will impact productive international cooperation among states.

At worst, it threatens to undermine states cooperation under the NPT, impede progress on the developing standards of non-proliferation verification, and divide states that do have a common interest in promoting disarmament.

The United States, of course, remains committed to advancing non-proliferation and disarmament goals of the NPT as well as increasing cooperation on the peaceful uses of nuclear energy. And I would just mention that two weeks after President Biden took office, the United States and Russia have extended the New START Treaty for five years. That’s the kind of arms control decision that, in the US view, makes the world safer and was really the beginning of renewed efforts in this administration to address nuclear threats.

About the author

Alexandra Perina is the Assistant Legal Adviser for Nonproliferation and Arms Control at the U.S. Department of State, leading the office that provides legal advice on the negotiation, interpretation, and implementation of arms control and nonproliferation agreements and arrangements, nonproliferation-related sanctions and assistance projects, and civil nuclear cooperation, among other programs.

She has served as an attorney in a variety of positions at the State Department for fifteen years, previously leading the Department’s legal offices for political-military affairs and for employment law, and has advised on issues ranging from the law of war and use of force, cyber, counterterrorism and intelligence matters, to environmental and maritime law, to personnel law and employment litigation.

From 2013-2014, she was an International Affairs Fellow in residence at the Council on Foreign Relations. Prior to joining the State Department, she worked as a litigator at Debevoise & Plimpton LLP in New York and as an associate at Human Rights Watch. Ms. Perina received a B.A. from Haverford College and a law degree from New York University School of Law.

Still, remember what we like to say on Lawfire^®: gather the facts, examine the law, evaluate the arguments – and then decide for yourself!