The prohibition on receiving transfer or control
As discussed in the previous section, one state not party — the United Kingdom — leases Trident missiles and imports other key nuclear components from the United States, which is not compatible with the TPNW’s prohibition on receiving the transfer of nuclear weapons or other nuclear explosive devices.
Each State Party undertakes never under any circumstances to: ‘Receive the transfer of or control over nuclear weapons or other nuclear explosive devices directly or indirectly.’
• To ’receive’ a nuclear weapon or other nuclear explosive device is to take possession or control over it. This broad notion does not require that ownership also pass to the recipient.
• The prohibition on indirect receipt covers accepting the key components of any nuclear weapon or other nuclear explosive device as well as an assembled version. This extends to transfers made through intermediaries.
• Article 1(1)(c) of the TPNW follows a similarly worded provision in Article II of the NPT, but the corresponding prohibition in that Treaty applies only to those States that are designated as non-nuclear-weapon states.
In 2020, the United Kingdom (UK) Secretary of State for Defence, Ben Wallace, urged the US Congress to support initial spending on developing a new nuclear warhead, the W93, which is intended for deployment on US SSBNs by 2040. A replacement for the United Kingdom’s Holbrooke warhead would be based on the W93. Nonetheless, in March 2021, the same Secretary of State declared in the UK House of Commons that: ‘For clarity, the United Kingdom does not buy warheads from other countries. Under the nuclear proliferation treaty, warheads have to be developed within that very country itself.’
Another potential future compatibility issue under this prohibition concerns the US B61 nuclear bombs stored in Europe. Arrangements are reportedly in place for control over the bombs to be given by the United States to the host states Belgium, Germany, Italy, and the Netherlands, for loading and use in their dual-capable NATO-designated aircraft. If this were to occur, the receiving state would contravene Article 1(1)(c) of the TPNW (and potentially also the NPT). This specific task division arrangement has therefore been much discussed, not least when the German Bundeswehr in 2008 handed out directives, in the form of a pocket card (‘Taschenkarte’), stipulating that German soldiers were prohibited from using nuclear weapons under international law. The directives have since been changed and the sentence in question omitted.
Belgium, Germany, Italy, and the Netherlands all have a nuclear role in NATO and retain the dual-capable aircraft and pilots trained in the use of the weapons at bases on their territory. The weapons are subject to ‘dual key’ authorisation by the United States government and the government of the respective host state in order to be used. In the case of the B61 bombs stationed at Incirlik in Turkey, however, any use of the weapons would reportedly be carried out by aircraft stationed at other bases, and it is not clear whether Turkey’s fighters maintain the capacity to drop nuclear bombs. There are ostensibly no nuclear-capable aircraft at Incirlik.
Belgium, the Netherlands, Italy, and Turkey have recently undergone, or are still undergoing processes to procure the F35-A fighter aircraft in order to fulfil the technical requirements of their nuclear-sharing arrangements. In the Netherlands, a majority of the members of parliament supported a motion stating that the F-35s should have no nuclear role. The Dutch government decided to ignore the parliamentary vote, opting to procure nuclear-capable F-35s. The final technical adjustments necessary to enable the F-35 to employ nuclear weapons (‘Block 4’) are expected to be implemented across the relevant host states between 2020 and 2024.
Germany decided in March 2022 to replace its ageing Tornado fleet, which includes nuclear-capable aircraft, with F-35 fighters. The decision was taken following Russia's invasion of Ukraine.
See the section on the prohibition on allowing stationing, installation, or deployment of nuclear weapons for further information on the US nuclear weapons stored in Europe.