The prohibition on assistance, encouragement, or inducement

A) Participation in nuclear strike exercises and joint manoeuvres

Assisting nuclear bombing raids or strikes, for instance with conventional air tactics, would undoubtedly constitute unlawful assistance to use nuclear weapons. Participation in exercises that involve the simulated use of nuclear weapons also contravenes Article 1(1)(e) of the TPNW. Specifically, participation in nuclear strike exercises would, in most conceivable scenarios, amount to encouragement of possession and development. After all, practising nuclear-weapon use implies an endorsement of the potential use of the weapons in the future and, by extension, an encouragement of the possession of nuclear weapons in the present. Nuclear-weapon-use exercises are frequently conducted precisely with a view to building collective resolve and commitment to continued possession as well as for potential use of nuclear arms in certain circumstances.

Czechia, Poland, and the five nuclear host states in NATO (Belgium, Germany, Italy, the Netherlands, and Turkey) all encouraged possession of nuclear weapons when, in October 2021, they participated in NATO’s annual nuclear strike exercise, ‘Steadfast Noon’, at Ghedi and Aviano air bases in Italy. The drill allows NATO members to practise use of the B61 nuclear bombs stationed in Europe. According to NATO, aircraft and personnel from 14 unnamed NATO states took part. However, plane spotters only identified aircraft from the seven mentioned above, in addition to the United States. The host states practised loading and dropping of inert nuclear bombs with their dual-capable aircraft, and Czechia and Poland likely practised air-cover manoeuvres using conventional fighter aircraft.

In November 2021, Australian and British personnel participated in the United States’ annual nuclear command and control exercise, ‘Global Thunder’, which simulated nuclear strikes against Russia in order to validate the various elements of the US nuclear triad. The US Government stated that ‘Allied personnel integrate into senior leadership teams and work across a broad spectrum of areas, offering public affairs and policy support, as well as deterrence and information operations insight’. This amounts to encouragement of possession of nuclear weapons, as prohibited under Article 1(1)(e) of the TPNW.

More broadly, participation by non-nuclear-armed states in nuclear strike exercises, when conducted in especially sensitive circumstances of tension or conflict, may also amount to prohibited assistance with threatening to use nuclear weapons (Article 1(1)(d)), provided that it acted with knowledge and that its participation was a significant contribution. (See the section above on the prohibition on threatening to use.)

Several non-nuclear-armed states routinely commit conventional fighter planes or other military capabilities to joint manoeuvres with US or Russian strategic bombers. The dual capability of strategic bombers renders unequivocal legal assessment of such participation difficult. Provided that the manoeuvres in question are not specifically ‘nuclear’, i.e. that the deployed strategic bombers are not practising for the use of nuclear weapons but are instead involved in conventional-weapon roles, participation by non-nuclear-armed states is not controversial under the TPNW. That said, the deployment of strategic bombers often has a clear nuclear signalling effect. In most cases, however, information about the true nature of such manoeuvres (and the roles of the various non-nuclear-armed states involved) is not available.

The year 2021 saw a number of joint manoeuvres that, in the absence of further information, cannot be said straightforwardly to contravene the prohibition in Article 1(1)(e) of the TPNW, but which nevertheless cast nuclear shadows over the participation of non-nuclear-armed states. On 17 May 2021, for example, F-16 fighters from Bodø Air Base in Norway conducted manoeuvres with an American B-52 strategic bomber just south of the Arctic circle. The Norwegian warplanes were reportedly engaged as ‘joint terminal attack controllers’, meaning they were practising close air support and other offensive air operations from a forward position.

Probably the closest example in 2021 to a joint manoeuvre (beyond the nuclear strike exercises discussed above) where participation might be incompatible with Article 1(1)(e) of the TPNW was when Russian nuclear bombers, flanked by Belarusian fighter jets, flew patrols over Belarus in November. The patrols were carried out amid a dispute between Belarus and the European Union concerning migration at the Polish–Belarusian border. The Belarusian President, Alexander Lukashenko, said: ‘Let them scream and squeak. Yes, those are nuclear-capable bombers, but we have no other choice.'

B) Logistical and technical support

The provision of logistical and technical support to, for instance, a submarine specifically designed to carry nuclear weapons, would likely constitute assistance with possession of the weapons, provided that the support is a significant contribution. Port visits by SSBNs are rare, however, as such submarines typically seek to remain undetected and untraceable while on patrol. In June 2021, a US SSBN visited the UK Naval Base in Gibraltar in what was termed an ‘exceedingly rare’ stopover.

In the case of logistical and technical support for dual-use delivery vehicles, such as B-52 bombers or F-35 fighter-bombers, there will normally be no presumption of nuclear involvement. It will therefore be generally unproblematic for states parties to the TPNW that are allies and partners of nuclear-armed states to continue to host or provide logistical and technical support to those states’ dual-use delivery vehicles. In 2021, for instance, multiple US B-52s were hosted at Al Udeid Air Base in Qatar. B-52s were also hosted at the Morón Air Base in Spain. There is no evidence that the aircraft in question were specifically engaged or deployed in nuclear roles. If the purpose of a mission or presence with a nuclear-armed state’s dual-use delivery vehicle is clearly nuclear, however, the provision of logistical and technical support is likely to contravene the prohibition on assistance to and encouragement of prohibited activities.

The five nuclear host states provide logistical and security services at the bases where US nuclear weapons are deployed to their territory. This constitutes assistance with possession and stockpiling. (Of course, these five states are also acting in conflict with Article 1(1)(g), which explicitly prohibits the hosting of another state’s nuclear weapons.)

C) Intelligence gathering and sharing

If a state party to the TPNW were to engage in intelligence gathering and share it with a nuclear-armed state to knowingly identify targets for a temporally proximate use or threat to use nuclear weapons, this would amount to assisting use or threatening to use nuclear weapons.

A concrete case in point is Pine Gap, an intelligence facility built and funded by the United States outside Alice Springs in Australia and operated by the US National Reconnaissance Office. More than 800 Australian and US personnel staff the facility, including members of units from all four branches of the US military. One of the components of the facility is a Relay Ground Station in Pine Gap’s western compound, whose Overhead Persistent Infra-Red (OPIR) sensors will detect the heat bloom of any ICBMs or SLBMs launched against the United States. It provides early warning of an incoming attack but also indicates whether a nuclear missile launch site/launcher is empty (following firing) or not.

If Australia were to adhere to the TPNW and the Relay Ground Station were nevertheless used to identify imminent targets for US nuclear weapons, this would violate the prohibition on assisting use or the threatening of use. (This would not be the case if the data were used to identify targets for conventional strikes or to alert a vulnerable target population.) Since such future use or threat to use nuclear weapons remains a theoretical possibility, the operations of the Relay Ground Station do not presently constitute assistance or encouragement to use or threaten to use nuclear weapons.

In so far as it applies to nuclear weapons, however, the current arrangement with the Australian government at Pine Gap is part of the United States’ nuclear-strategic infrastructure and can thus be considered a manifestation of Australia’s encouragement of continued US possession of such weapons. Maintaining a capability and preparedness to identify targets for nuclear strikes also runs counter to the object and purpose of the TPNW. To ensure compatibility with the TPNW, Australia would therefore have to take the necessary action to provide assurances that the Relay Ground Station’s OPIR systems will not be used for nuclear targeting.

D) Participation in nuclear planning

Participation in nuclear strike planning entails an endorsement of the potential use of nuclear weapons in the future and, by extension, an encouragement of the possession and development of nuclear weapons in the present. Participation in planning of temporally proximate use or threats to use nuclear weapons would amount to assistance with use or the threatening of use. As discussed above, Australia was involved in nuclear planning and preparations in 2021 through its participation in the US nuclear command and control exercise Global Thunder, in contravention of Article 1(1)(e) of the TPNW.

From this perspective, participation in NATO’s Nuclear Planning Group (NPG) — the alliance’s senior body on nuclear strategy — is not compatible with Article 1(1)(e) of the TPNW. In the view of the Nuclear Weapons Ban Monitor, however, the TPNW does not necessarily preclude continued membership and participation in the NPG. The decisive criterion would be what happened inside the group. A state party to the TPNW could, for example, use its participation in the NPG only to promote nuclear disarmament.

Japan and South Korea on their part are engaged in ‘extended deterrence dialogues’ with the United States. To the extent that such dialogue is on general nuclear deterrence where future use is theoretical, their participation should be considered as encouragement of possession. To the extent that the dialogue concerns specific targets and is directed and communicated towards a specific adversary, it could also amount to assistance to threatening to use nuclear weapons. Any assessment is largely context-dependent. Thus, if Japan and South Korea were to adhere to the TPNW in the future, they would have to provide assurances that their respective ‘extended deterrence dialogues’ with the United States would not involve nuclear strike planning or target selection

E) Allowing the testing of missiles designed to carry nuclear warheads

Permitting the testing of missiles designed to carry nuclear warheads on one’s territory is not consistent with the TPNW’s prohibition on assistance with development of nuclear weapons. Two states (Kazakhstan, which is a state party, and the Marshall Islands, which is undecided on the TPNW) host test sites that have regularly served as the destination point for long-range missile tests carried out by Russia and the United States, respectively. In Kazakhstan, the site in question is the Sary-Shagan test site, a missile range established by the Soviet government in 1956. In the Marshall Islands, the site in question is the Ronald Reagan range at Kwajalein Atoll, a military station established after the Second World War. In both cases, the land on which the site is located is leased to the respective nuclear-armed state through long-term agreements. It is not the testing sites in and of themselves that conflict with the TPNW, but Russia’s and the United States’ use of them to maintain and develop nuclear-weapon missile technology.

The Reagan Test Site at Kwajalein Atoll was the destination point for at least two US ICBM tests in 2021. Should the Marshall Islands decide to adhere to the TPNW, such testing would need to stop if it involved nuclear-capable missiles. Marshallese adherence to the TPNW could thus lead to friction with the United States, perhaps helping to explain the Marshall Islands’ hesitancy about joining the Treaty. With its long history as a testing ground for US nuclear weapons, the Marshall Islands has been a strong supporter of nuclear disarmament and the campaign to end nuclear testing.

With respect to Kazakhstan, there is no evidence that Russia used the Sary-Shagan site to test missiles designed to carry nuclear warheads in 2021. Sary-Shagan appears not to have been used as the destination point for ICBM tests for some time now, possibly in reaction to Kazakhstan’s ratification of the TPNW. In fact, Russian officials have recently noted the problem of not having testing grounds on Russian soil, and Russia has reportedly begun constructing a new missile test site on Russian territory. (See: H. M. Kristensen and M. Korda, ‘Russian nuclear weapons, 2021’, Bulletin of the Atomic Scientists, Vol. 77, No. 2 (2021)). As a state committed to the goals of the TPNW, Kazakhstan should communicate its priorities to Russia and request that it continues to abstain from using the Sary-Shagan site for testing any missiles that can carry nuclear warheads.

It will be necessary to discuss these and other difficult compliance questions in a transparent manner, including at the TPNW’s meetings of states parties. Compliance and adherence will continue to build the norms established by the TPNW, and compliance issues arise in the implementation of almost every disarmament treaty. Kazakhstan, a nation that once inherited more than a thousand Soviet nuclear weapons and voluntarily relinquished them, is a long-time advocate of a world free of nuclear weapons. Together with its Central Asian neighbour-states, Kazakhstan established the Central-Asian NWFZ Treaty, which similarly obligates its member states not to ‘assist’ the development or manufacture of nuclear weapons.

It has been suggested that the obligation in TPNW Article 4(2) to ensure ‘the elimination or irreversible conversion of all nuclear-weapons-related facilities’ obligates Kazakhstan to close the Sary-Shagan site. However, Article 4(2) applies to any state that ‘owns, possesses or controls nuclear weapons or other nuclear explosive devices’ and can therefore not be applied to Kazakhstan. To the extent that Sary-Shagan is ‘clearly connected to Russia’s nuclear weapon complex’, any responsibility to eliminate or irreversibly convert the Sary-Shagan test site under Article 4(2) would fall on Russia.

F) Endorsement of nuclear-weapons doctrines, policies, and statements

All of NATO’s member states (the 27 umbrella states and the 3 nuclear-armed states) contravene Article 1(1)(e) of the TPNW through specific nuclear-related doctrines, policies, and/or statements to which they subscribe. NATO’s foundational document, the North Atlantic Treaty, does not mention nuclear weapons, but every NATO member has supported possession and potential use of nuclear weapons through their endorsement of various other alliance documents, particularly the Strategic Concept. None of the alliance’s members has so far rejected the possession or use, or even the first use, of nuclear weapons on its behalf. In the view of the Nuclear Weapons Ban Monitor, their endorsement of the Strategic Concept amounts to encouragement of possession of nuclear weapons. It does not, however, amount to encouragement of use, as that would require, for instance, a request for use of nuclear weapons in a specific context, or agreeing to rules of engagement allowing the use of nuclear weapons in a concrete multinational operation.

Three non-NATO US allies (Australia, Japan, and South Korea) also encourage possession of nuclear weapons through explicit statements they have made or strategy documents they have endorsed. For example, the governments of the United States and Japan expressed through a joint statement in 2013 that they remained committed to the security of Japan ‘through the full range of US military capabilities, including nuclear and conventional’. South Korea has endorsed similar statements with respect to its own position. In 2016, Japan and South Korea (together with France and the United Kingdom) reportedly expressed opposition to the Obama administration’s plans of adopting a nuclear no-first-use policy.

With respect to Australia, the most recent example of a government document which appears to directly encourage the United States to retain nuclear weapons was published in 2020, stating that ‘only the nuclear and conventional capabilities of the United States can offer effective deterrence against the possibility of nuclear threats against Australia.’

In addition to NATO, the Russian-led Collective Security Treaty Organization (CSTO) is understood by some observers as a ‘nuclear alliance’. In 2010, the CSTO’s Secretary-General suggested Russia had extended a ‘nuclear umbrella’ over all members of the alliance. Yet, CSTO members do not appear to have adopted official documents stipulating a nuclear dimension to the alliance. On the contrary, three members have actively distanced themselves from nuclear deterrence. Through the 2006 Treaty of Semipalatinsk — the treaty establishing Central Asia as an NWFZ — Kazakhstan, Kyrgyzstan, and Tajikistan have committed never to ‘assist or encourage’ the development, manufacture, or possession of nuclear weapons. Kazakhstan is also a state party to the TPNW.

Belarus, however, which is allied to Russia through the CSTO and the Union State, has on multiple occasions expressed support for nuclear deterrence, and its conduct is therefore not compatible with the TPNW’s prohibition on encouragement of possession of nuclear weapons. Armenia, the last CSTO member, has, to the Nuclear Weapons Ban Monitor’s knowledge, not explicitly endorsed the possession and potential use of nuclear weapons on its behalf. Armenia would, though, need to actively distance itself from nuclear deterrence in order to be considered compliant with Article 1(1)(e) of the TPNW, as fellow CSTO members Kazakhstan, Kyrgyzstan, and Tajikistan have already done through their adherence to the Treaty of Semipalatinsk, and in Kazakhstan’s case also to the TPNW.

For an overview of arrangements of extended nuclear deterrence (‘nuclear umbrellas’), see the table below.

Some nuclear umbrella arrangements are formalized in writing and others are not. They have all emerged as supplements or in parallel to general military alliances. None of the existing, underlying legally binding mutual defence treaties mentions nuclear weapons specifically. Nuclear umbrellas should therefore be understood as political, not legal arrangements. The then Norwegian Foreign Minister Ine Eriksen Søreide declared in the Norwegian Parliament in November 2018 that ‘there is no legal obligation barring Norway from signing or ratifying the TPNW’. The obstacle, she argued, was ‘political commitments’.

Through their continued endorsement of nuclear deterrence, umbrella states contribute to the resolve of nuclear-armed states to continuously modernize and maintain their capabilities. Nuclear-armed states often assert a need on behalf of non-nuclear allies and partners to ‘assure’ and fulfil ‘extended deterrence commitments’ as pretexts for their nuclear deployments and modernization programmes, including the building of new capabilities. The US Mission to NATO stated in a tweet in August 2020 that ‘NATO needs nuclear weapons because our nuclear deterrent is the ultimate security guarantee for Europe. For 70 years nuclear weapons have kept adversaries at bay & provided reassurance for Allies.’ Experts even describe the ability to deter escalation of potential Russian and Chinese conflict with US allies as the ‘primary role’ of US nuclear weapons today.

In the United Kingdom, the government’s push for a full replacement of the Vanguard-class SSBNs in 2016 was based on the argument that NATO was a ‘nuclear alliance’ and that the United Kingdom thereby had no choice but to renew its arsenal of weapons of mass destruction.

In France, President Emmanuel Macron has recently re- launched the idea of a ‘European’ nuclear posture enacted by Paris. Specifically, the President has invited interested European states to take part in a dialogue about the French nuclear arsenal’s supposed contribution to European security. Similar initiatives have been made by most French governments since the 1960s, albeit with few takers and little enthusiasm among other European states.

* New Zealand was de facto excluded from ANZUS in the mid-1980s due to its anti-nuclear-weapon policies.

G) Development, production, and maintenance of key components for nuclear weapons

Numerous private companies are engaged in work linked to nuclear weapons. Most defence contractors involved in the nuclear enterprise are headquartered in the nuclear-armed states. However, some have headquarters or divisions in non-nuclear-armed states. As a result, as discussed below, the conduct of non-nuclear-armed Belarus, Italy, Germany, and the Netherlands is not compatible with the prohibition on assisting development and manufacturing nuclear weapons because they allow companies that are incorporated or have headquarters or production facilities on their territory to be involved in the development of nuclear weapon systems.

• The Belarusian company Minsk Automobile Plant is the only manufacturer of the mobile launchers for the Russian Topol-M ICBM.
• The German-headquartered company Airbus Defence and Space is currently involved in the development and production of French nuclear weapons. This development takes place within the framework of the joint venture company MBDA, which produces France’s air-launched cruise missiles, and the joint venture company ArianeGroup, which is the lead contractor for both France’s M51 nuclear-tipped SLBMs and the next generation of nuclear-tipped air-launched cruise missiles. Airbus Defence and Space is a subdivision of Airbus, which is headquartered in the Netherlands. Since Airbus considers that the actions of its subsidiaries form part of the work of Airbus as a group entity, both Germany and the Netherlands may be understood to presently be engaged in activities prohibited under Article 1(1)(e) of the TPNW.
• The Italian company Leonardo (formerly Finmeccanica) is also involved in the development and production of France’s current nuclear-tipped air- launched cruise missiles through the joint venture MBDA (with Airbus and BAE Systems).

H) Nuclear cooperation arrangements

The United Kingdom and France are engaged in close cooperation on maintenance of nuclear stockpiles, which amounts to prohibited (mutual) assistance with possession and stockpiling under the TPNW. The two states’ cooperation on stockpiling is supported by the 2010 Teutates Treaty to develop technologies for safe and effective maintenance of both states’ nuclear stockpiles.

US–French cooperation is conducted under a 1961 Mutual Defense Agreement, which permits limited cooperation on the operation of nuclear-weapon systems. Later amendments have enabled enhanced cooperation, notably on issues of safety, security, and reliability.

As discussed above under the prohibitions on transfer and on receiving transfer or control of nuclear weapons or other nuclear explosive devices, the United Kingdom and the United States continue to engage in close cooperation on Trident II SLBMs. The nature of the cooperation also amounts to US assistance with the United Kingdom’s
development of nuclear weapons.

I) Financing of prohibited activities

According to the 2021 Pax/ICAN Don’t Bank on the Bomb report ‘Perilous Profiteering’, the total amount of loans offered to companies involved in the production and maintenance of nuclear weapons increased in 2021 compared to the previous year. At the same time, the number of investors decreased. In 2021, the year the TPNW
entered into force, as many as 127 financial institutions divested from companies involved in the nuclear-weapons business. This was a significant increase on previous years, suggesting the TPNW had a significant impact on the financial sector.

For example, in November 2021, Norway’s biggest pension fund, KLP, announced its decision to divest from a range of companies involved in the production of maintenance of nuclear weapons, including Larsen & Toubro, Leidos, Leonardo, Raytheon, Rolls Royce, and Thales. The companies in question were considered to be undermining the goal of creating a world without nuclear weapons in line with the TPNW. In the words of the fund’s head of responsible investments, KLP wanted ‘to support the aim of the UN Treaty on the Prohibition of Nuclear Weapons, which came into force in January, and therefore had to apply stricter standards to firms that contributed to the continuing existence of such arms.’

Also in 2021, as ‘a result of a changing international norm, with the Treaty on the Prohibition of Nuclear Weapons entering into force in January 2021’, the Responsible Investment Association Australasia (RIAA) announced it will not certify financial products that involve investment in companies that produce nuclear weapons. RIAA promotes responsible investing in Australia and New Zealand.

e) Financing of prohibited activities

The development, production, and maintenance of nuclear weapons constitutes a multi-billion-dollar industry, with numerous large companies and universities profiting from, and lending their legitimacy to, the industrial effort. The TPNW does not explicitly prohibit financing of nuclear-weapon programmes. However, the prohibition on assistance renders unlawful direct funding of any of the prohibited activities listed in the other subparagraphs of Article 1(1). If, for instance, funding in the form of an earmarked loan or a credit line is provided to a company for the development or maintenance of nuclear weapons, this is unlawful assistance with the development or possession of nuclear weapons.

The prohibition on financing encompasses not only state funding, including sovereign funds, but also private banks and individuals, as discussed above in the subsection on corporate and state responsibility. The ordinary purchase of shares in a company involved in the development, production, or maintenance of nuclear arsenals is not per se an illegal act under the TPNW, although ownership could be assessed differently depending on the amount of shares purchased and divestment from such companies is a growing trend.

Cuba issued a declaration upon joining the TPNW, stating that ‘The financing of any activity prohibited to a State Party under this Treaty is also a prohibited activity according to the provisions of Article 1(e)’. The prohibition on assistance also appears in the CCM, where it is widely considered to prohibit financing.

f) Uranium mining and export

Under international law, mining and transfer of uranium is generally lawful, unless it is for the purpose of developing or assisting in the development of a nuclear explosive device. The peaceful use of nuclear energy is protected under Article IV of the NPT, and the Preamble to the TPNW confirms that nothing in the Treaty should be interpreted as affecting that right. A state may therefore extract uranium and either use the nuclear material itself or provide it to another state for peaceful purposes, as long as it is subject to Safeguards Agreements with the International Atomic Energy Agency (IAEA).

Under the TPNW, the provision of uranium to any other state is prohibited where it is not subject to appropriate Safeguards Agreements or if the state party transferring the uranium knows that the material in question will, or is likely to, be used to develop a nuclear weapon or other nuclear explosive device. Otherwise, states parties to the TPNW are permitted to transfer uranium, including to nuclear-armed states and states not party to the TPNW. Several states that mine and export uranium are states parties to the TPNW, including Kazakhstan, Namibia, and South Africa.

Under the NPT, the provision of uranium to any non-nuclear-weapon state is unlawful where it is not subject to appropriate Safeguards Agreements. The NPT does not directly address the legality of provision of uranium to the five nuclear-weapon states designated under that Treaty.

If a state exports uranium to a nuclear-armed state or any other state on the understanding that the uranium would be used exclusively for peaceful purposes, the exporting state could not be considered to be in violation of either the TPNW or the NPT if the importing state unexpectedly decided to use the uranium for weapons development instead. This would, though, be likely to affect the legality of future exports of uranium to that state.

When armed groups control areas of a state’s territory or when an armed conflict is ongoing, situations could occur where it would be difficult for the authorities of a state in which uranium deposits exist to effectively control all extraction and transfers. If a non-state actor in such a situation were to transfer uranium to an actor intending to develop a nuclear explosive device, the territorial state could not be considered to be in violation of either the TPNW or the NPT, provided that it has made all reasonable efforts to prevent such extraction and transfers. All reasonable efforts would include the adoption of national legislation and implementation of other practical measures, to secure as far as possible sites in which uranium is present or where stocks of uranium are held.