Holding answer received on 17 October 2014
The 1958 UK-US Mutual Defence Agreement is a bilateral treaty which provides the basis of the UK’s relationship with the US in respect of nuclear propulsion and nuclear warheads.
Most of the activity carried out under the treaty comprises exchanging information, which takes place through a series of joint working groups.
In addition, there are two enhanced collaborations, which are focused on developing capabilities:
Enhanced Nuclear Safety – the objective of which is to develop architectures and technologies related to warhead safety.
Warhead Electrical System – the objective of which is to develop architectures and technologies related to warhead electrical systems.
Both enhanced collaborations contribute to ensuring that the UK maintains our nuclear warhead stockpile on a continuing basis.