Nuclear Coalitions and the Ban Treaty: A Reaction to the First Draft Treaty Text

By Daniel Rietiker (PhD), on behalf of Swiss Lawyers for Nuclear Disarmament (SLND – SAFNA)[1]

June 6, 2017


In the ongoing negotiations with a view to adopting a treaty prohibiting nuclear weapons (“ban treaty”), the question whether States hosting nuclear weapons on their territory or relying on a nuclear umbrella should be able to engage in such a treaty – and if so how and to what extent? – is particularly difficult.[2] The present analysis focuses exclusively on the legal implications and challenges of such a scenario. It is also a reaction to the first draft treaty text submitted by the President of the Conference to negotiate a legally binding instrument to prohibit nuclear weapons leading towards their total elimination, released on May 22, 2017.[3]

The following observations rely on two fundamental premises: First, it is agreed upon that the new treaty is primarily about “norm-building”. In other words, the more States join the treaty the better since their ratifications can be taken into account as an expression of an opinio juris to be bound by a customary rule prohibiting nuclear weapons.[4] It might therefore be argued that allies of Nuclear Weapons States (NWS) shall not only be allowed to join the treaty, but even be encouraged to do so. If such an approach is certainly defendable, they should not be allowed to become Parties unconditionnally, in particular not by deceiving the object and purpose of the new treaty. It follows that the negotiating States have to find a compromise between the accomodation of the particular interests of those States, on the one hand, and the integrity of the treaty and the principle of equal treatment, on the other. This balance will be addressed in the first part of the analysis dealing with the duty to abstain from certain acts.

Second, it is also commonly accepted that a ban treaty is not an aim itself, but only a first (or another) step towards general and complete disarmament. In other words, the negotiating States want to make sure that, one day, the NWS will give up their weapons. Who else than the allies of the NWS, if committed to a ban on nuclear weapons, are better placed to put pressure on the NWS in view of nuclear disarmament? Following this logic, it could be argued that the allies of NWS shall not only be allowed to ratify a ban treaty but, beyond that, be encouraged to engage in favor of disarmament vis-à-vis NWS. This aspect will be briefly discussed in the second part devoted to positive obligations.

I. The duty to abstain from assisting in the commission of prohibited acts

The first question to be raised is whether a State Party, through mere military cooperation with NWS, should be excluded per se from the new treaty? The first draft ban treaty text does not give an explicit answer and, as a result, does neither allow nor prohibit such cooperation, contrary to an earlier arms control treaty. Indeed, under the 2008 Cluster Munitions Convention (hereafter: the Oslo Convention), interoperability is basically allowed by virtue of paragraph 3 of Article 21:

“Nothwithstanding the provisions of Article 1 of this Convention and in accordance with international law, States Parties, their military personnel or nationals, may engage in military cooperation and operations with States not party to tis Convention that might engage in activities prohibited to a State Party.”

Paragraph 4 of Article 21 clarifies, however, that States Parties are not supposed to breach themselves the treaty, in particular by developing, transfering possessing or using those weapons.[5] It is, from our point of view, not excluded to propose a similar provision in the future treaty prohibing nuclear weapons, should this be considered envisageable in practice.

Moreover, it is common practice, in recent arms control treaties, to include a general clause prohbiting assistance, encouragement and inducement to acts prohibited by the treaty. This is the case, inter alia, for the Chemical Weapons Convention (CWC),[6] the Biological Weapons Convention (BWC)[7], the Oslo Convention, as well as the Ottawa Convention on anti-personnel mines.[8] In its Article 1 § 1 f), the first draft ban treaty also contain such a clause:

“Each State Party undertakes never under any circumstances to (…) [a]ssist, encourage, or induce, in any way, anyone to engage in any activity prohibited to a State Party under this Convention.”

The wording of this clause is standard and, as a result, should find general support in the upcoming negotiations. Its inclusion seems appropriate since, by prohibiting assistance to “anyone”, such clauses go further than what is proposed by general international law. In fact, Article 16 of the International Law Commission’s (IlC) Draft Articles on Responsibility of States for Internationally Wrongful Acts[9] prohibits aid or assistance of another State in the commission of an internationally wrongful act by the latter only if the act would be internationally wrongful if committed by that State. As far as a new treaty prohibiting nuclear weapons is concerned, this would, from our point of view, be the case for the use (and threat of use) of nuclear weapons, but not necessarily for other acts prohibited by the treaty.[10]

Such clauses prohibiting assistance are likely to restrict heavily the freedom of behavior of States vis-à-vis their coalition partners. In other words, there would in practice not be much room for cooperation with NWS.[11] This can be deduced, first of all, from the restrictive vocabulary used in those clauses (“never under any circumstances”, “in any way”, and “anyone”).

The extent of restriction in the relationship between NNWS (Non Nuclear Weapons State) and NWS would moreover depend, in a treaty banning nuclear weapons, on the interpretation of the verb “to assist”; would it mean stationing or deploying nuclear weapons in its own territory? Would it cover participation in planning of potential use or joint trainings, or should it be a more qualified behavior?[12] In light of those uncertainties, SLND welcome the inclusion in the first draft of the future ban treaty of the following clause:

Each State Party undertakes to prohibit and prevent in its territory or at any place under its jurisdiction or control:

a) Any stationing, installation or deployment of any nuclear weapons or other nuclear explosive devices; b) Any nuclear weapon test explosion or any other nuclear explosion.”[13]

II. The duty to refrain from requesting use of nuclear weapons on its own behalf

A different, but related question is whether a State Party to the new treaty can be defended by a State not Party by means of use of nuclear weapons or, in other words, benefit from a nuclear umbrella without breaching the treaty? Such a State could be in an alliance without actively participate in nuclear arrangements but still have an interest in being defended by a NWS when attacked by another State. Shall such a behavior be tolerated under a ban treaty? As far as, mutatis mutandis, a treaty prohibiting nuclear weapons is concerned, the actual draft treaty does not address that question.

SLND are of the opinion that there exist relevant internatinal practice in this field. It can be recalled that the Tlatelolco Treaty establishing a Nuclear Weapon Free Zone (NWFZ) in Latin America and the Caribbeans provides for the following provision:

“The Contracting Parties also undertake to refrain from engaging in encouraging or authorizing, directly or indirectly, or in any way participating in the testing, use, manufacture, production, possession or control of any nuclear weapon.”[14]

In the same vein, but in the field of conventional weapons, the Oslo Convention includes a similar, even more explicit provision prohibiting to request the use of cluster munitions:

“Nothing in paragraph 3 of this Article [allowing military cooperation between States Parties and States not Parties] shall autorize a State Party (…) to expressly request the use of cluster munitions in cases where the choice of munitions used is within its exlusive control.”[15]

The inclusion of such a clause in the ban treaty might be useful. It might, however, not be appropriate to restrict such a prohibition to a “express” request, and, moreover, to situations where the choice of weapons used is within the State Party’s exclusive control, since in a nuclear alliance or coalition, it might not always be up to a certain State alone to take the decision to use those weapons.

In those lines, a paper submitted by International Association of Lawyers for Nuclear Arms (IALANA) proposed a clause that could read as follows:

“Each State Party undertakes not to request and not to accept the use or threatened use of nuclear weapons on its behalf by a non-State Party, and not to encourage or authorize, directly or indirectly use and threatened use of nuclear weapons.”[16]

Contrary to the Oslo Convention and in order to generally delegitimize nuclear weapons and nuclear deterrence, it seems appropriate to include a prohibition to request and not to accept the threat of use of nuclear weapons.

III.  Positive obligations

Article 21 §§ 1 and 2 of the Oslo Convention impose on the State Parties certain “positive” obligations with a view to promoting the aims of this treaty. Paragraph 1 reads as follows:

“Each State Party shall encourage States not Party to this Convention to ratify, accept, approve or accede to this Convention, with the goal of attracting the adherence of all States to this Convention.”

This is quite a surprising innovation in international law and it is also proposed in the actual draft ban treaty (Article 13: universality). SLND welcome such a clause. It is of course up to the States to decide, as a matter of equal sovereignty, what treaties they want to ratify, but it is certainly not against the law to include in a treaty the duty to convince and induce States not Parties to join a certain instrument. From our point of view, this underlines the erga omnes nature of certain of the duties deriving from the Oslo Convention and the potential ban treaty. Such a duty obviously aims at enhancing the number of States Parties and, in other words, universality of the treaty.

A second tool to promote the aims of the new treaty prohibiting nuclear weapons could be inspired by paragraph 2 of Article 21 of the Oslo Convention, which reads as follows:

“Each State Party shall notify the governments of all States not Party to this Convention, referred to in paragraph 3 of this Article, of its obligations under this Convention, shall promote the norms it establishes and shall make its best efforts to discourage States not Party to this Convention from using cluster munitions.”

The actual draft ban treaty does not propose such a clause. Referring to paragraph 3 of Article 21, this clause deals with interoperability within military alliances and coalitions. It means that a State Party has to inform their partners in such a cooperation that they are bound by this convention and shall make positive steps to encourage the partners not to use those weapons. Another IALANA paper proposes the inclusion of such a clause in the new treaty banning nuclear weapons, which could be formulated as follows:

“Each State Party shall promote the norms affirmed by this Treaty and shall make its best efforts to discourage States not Party to this treaty from possessing, using, or threatening the use of nuclear weapons.“

This clause is broader than Article 21 § 2 because it is as such not restricted to use of the prohibited weapons. Moreover, it is not limited to situations of cooperation within military allies involving NWS and NNWS.

Final remarks

If it is agreed upon that the new treaty is mostly about norm-building, the highest possible number of States Parties should be aimed at since those ratifications reflect a convinction (opinio juris) that the treaty could eventually express customary law. For that reason, the inclusion in the ban treaty of a clause on universality (draft article 13) is appropriate.

In theory, there are legal tools that seem flexible enough to accomdate the particular interests of allies of NWS and umbrella States, but the difference between nuclear weapons and cluster munitions should not be underestimated. In practice, to strike a fair balance without deceiving the object and purpose of the treaty might be difficult to achieve. In other words, allowing interoperability as such and, in the same time, prohibiting “assistance” to the acts prohibited by the treaty seems a priori hard to conciliate because military and strategic doctrines of umbrella States might embrace or count on nuclear weapons.[17]

Much will depend on the interpretation of a possible clause allowing interoperability in the sense of Article 21 § 3 of the Oslo Convention – the first draft does not propose such a provision which does not mean that interoperability is per se prohibited by the treaty. But an interpretation of such a clause too broadly in favor of military considerations would however endanger the object and purpose of the new treaty whose aim is, in particular, to exclude civilians suffering as a result of nuclear weapons use.[18] In this field, a positive duty to discourage nuclear weapons use by States not Party should be conceived broadly and assessed in light of rules and principles of international humanitarian law, in particular the duty to respect and ensure respect of humanitarian law in all circumstances within the meaning of common Article 1 of the Geneva Conventions. Moreover, another factor will be the exact formulation of the clause prohibiting assistance in the acts prohibited by the treaty and how the verb “to assist” will be interpreted subsequently. SLND support the comprehensive prohibition to assist, encourage or induce anyone in the commission of the acts prohibited by the treaty (draft Article 1 § 1 f) and the further clarification given in paragraph 2 of draft Article 1.

SLND are of the opinion that the Oslo Convention constitutes an interesting template for positive obligations, from which delegations negotiating the new treaty can get inspiration. Such inspiration is even more indicated having regard to the humanitarian spirit of the Oslo Convention and the fact that the new treaty follows the same logic. Therein, allies of NWS are particularly well placed to put pressure on those States in view to renounce their weapons, and, as a result, to contribute to a world free of nuclear weapons and to general and complete disarmament. Therefore, SLND are of the view that this fact could be taken into account by the inclusion in the ban treaty of a clause similar to Article 21 § 2 of the Oslo Convention in case interoperability shall basically be allowed under the treaty.

[1] This paper is an elaborated version of the panel contribution by Daniel Rietiker presented in the side event to the NPT First Preparatory Review Conference, May 2, 2017, “Nato, Nuclear Weapons and the Ban Treaty?”.

[2] See, for instance, International Law and Policy Institute (ILPI), Nuclear Umbrellas and Umbrella States,

[3] UN Doc. A/CONF.229/2017/CRP.1.

[4] Article 38 § 1 b) of the Statute of the International Court of Justice (ICJ), international custom is “a general practice accepted as law”.

[5] Article 21 § 4 reads as follows: “Nothing in paragraph 3 of this Article shall authorise a State Party: a) To develop, produce or otherwise acquire cluster munitions; b) to itself stockpile or transfer cluster munitions; c) To itself use cluster munitions (…).”

[6] Article I § 1 d) CWC.

[7] Article III of the BWC.

[8] Article I § 1 c) of the Ottawa and Oslo Conventions.

[9] Adopted by the ILC at its fifthy-third session, in 2001, and submitted to the UNGA as a part of the ILC’s report covering the work of that session (A/56/10).

[10] IALANA Discussion Paper, Selected Elements of a Treaty Prohibiting Nuclear Weapons, March 24, 2017, pp. 1-3,

[11] A. Breitegger, Cluster Munitions and International Law – Disarmament with a human face? Routledge, London and New York, 2012,  p. 185, indicates that many instances of cluster munition use occurred during joint operations, including the 1991 Operation Desert Storm, the 1999 Operation Allied Forces, the 2001 Operation Enduring Freedom and the 2003 Operation Iraqi Freedom.

[12] International Law and Policy Institute (ILPI) and UNIDIR, A Prohibition on Nuclear Weapons, A Guide to the Issues, 2016, p. 36.

[13] Article 1 § 2 of the draft treaty.

[14] Article 1 § 2 of the Tlatelolco Treaty.

[15] Article 21 § 4 letter d) of the Oslo Convention.

[16] IALANA Discussion Paper, op.cit., p. 8,

[17] ILPI and UNIDIR, op.cit., p. 36.

[18] See, mutatis mutandis, Breitegger, op.cit., p. 185.

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