The prohibition on transfer of nuclear weapons
One state not party – the United States – engaged in conduct in 2020 which was not compatible with the prohibition on transfer of nuclear weapons, by virtue of its export of key components to the United Kingdom’s nuclear weapons.
- The transfer of any nuclear weapon or other nuclear explosive device or control over them ‘to any recipient whatsoever’ is prohibited under Article 1(1)(b) of the TPNW. This is so whether this occurs ‘directly or indirectly’.
- This also makes it illegal to transmit possession or ownership to any other state or to any natural or legal person (e.g. a company or organisation) of key components of any nuclear explosive device in separate instalments or via intermediaries or third parties where there is knowledge they will be used to produce a nuclear weapon or other nuclear explosive device.
- Unlawful transfer does not necessarily involve payment or other form of consideration.
- Under Article I of the NPT, the five nuclear-weapon states parties have committed never to transfer nuclear weapons ‘to any recipient whatsoever’. The NPT does not include a corresponding prohibition on non-nuclear-weapon states to transfer nuclear weapons or other nuclear explosive devices or to assist in a transfer. These important lacunae are addressed by Article 1(1) (b) and (e) of the TPNW.
The United Kingdom’s nuclear-weapon system is in large measure imported from the United States: its nuclear warhead design (built in the UK) is based directly on the US W76; the Trident submarine-launched ballistic missile (SLBM) guidance system and a number of Trident warhead components are imported directly from the United States; the Trident detonator is designed and built in the United States; and the United Kingdom’s Trident II SLBMs are on lease from the United States. Whether this arrangement is compliant with the corresponding prohibition on transfer by nuclear-weapon states under the NPT is also highly questionable.
As noted in the section on the prohibition on development, UK officials have reportedly lobbied the US Congress to support the development of a new warhead, the W93, on which a new UK Trident warhead would presumably be based.