The prohibition on transfer
As was the case the previous year, in 2023 one state not party—the United States—engaged in conduct that was not compatible with the TPNW’s prohibition on transfer of nuclear weapons, by virtue of its export of key components to the United Kingdom’s nuclear arsenal.
The UK nuclear-weapon system is, in very large measure, imported from the United States. The United Kingdom leases its Trident II (D5) submarine-launched ballistic missiles (SLBMs) from the United States’ missile inventory; the design for the UK’s Holbrook nuclear warhead for its Trident missiles is partially based on the US W76 design; the Mk4A re- entry vehicle for the Holbrook warhead is imported from the United States; and key components of the UK’s nuclear- powered ballistic missile submarines (SSBNs) (the Trident SLBM fire control system and missile compartment) are also imported from the United States. These transfers of key components also violate the corresponding prohibition on transfer by nuclear-weapon states in Article 1 of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT).
For more information, see the 2023 edition of the Nuclear Weapons Ban Monitor.
Each State Party undertakes never under any circumstances to: ‘Transfer to any recipient whatsoever nuclear weapons or other nuclear explosive devices or control over such weapons or explosive devices directly or indirectly.’
- ‘Transfer’ means to transmit either possession or ownership. ‘Control’ means the power to use a nuclear weapon or nuclear explosive device.
- Since transfer is prohibited ‘to any recipient whatsoever’ and this is irrespective of whether it occurs ‘directly or indirectly’, it is also 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 weapon or other nuclear explosive device. This applies whether the transmission occurs 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.
- Providing another state with sufficiently detailed technical information for a nuclear warhead or other nuclear explosive device to be developed, and in the knowledge that it will be so used, would also constitute indirect transfer under Article 1(1)(b) of the TPNW. This is in addition to assistance with development under Article (1)(1)(e).
- Unlawful transfer does not necessarily involve payment or other form of ‘consideration’.
Under Article 1 of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), the five nuclear-weapon states parties have already committed never to transfer nuclear weapons ‘to any recipient whatsoever’, also whether this occurs ‘directly or indirectly’. - The NPT does not include a corresponding prohibition on non-nuclear-weapon states to assist in a transfer of nuclear weapons or other nuclear explosive devices. This important lacuna is addressed by Article 1(1)(b) and (e) of the TPNW.