Question to the Foreign, Commonwealth & Development Office:

To ask Her Majesty's Government what is their response to Leading by Example: Reforming UK Nuclear Declaratory Policy, the briefing by the British American Security Information Council, and, in particular, its recommendation that the UK should maintain its lead role in multilateral disarmament by (1) explicitly declaring that UK nuclear weapons are only there to deter nuclear use or blackmail when the survival of the UK is in question, (2) strengthening the UK's negative security assurances to non-nuclear states, (3) committing never to use nuclear weapons first, and (4) clarifying that the UK's nuclear weapons are weapons of last resort, and what is meant by that.

The UK's independent nuclear deterrent remains essential for our security. But we are committed to maintaining the minimum amount of destructive power needed to deter any aggressor. We also have a strong track record on nuclear disarmament, reducing our nuclear forces by over half since the Cold War peak in the late 1970s. We intend to maintain a leading role in multilateral disarmament efforts; unilateral disarmament would undermine our security and not make the world a safer place. We regret that Russia is making a number of destabilising nuclear and missile investments and undermining existing arms control Treaties, and DPRK is developing its illegal nuclear programme in violation of UN Security Council Resolutions; this makes progress more difficult. We are fully committed to ensuring that the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) remains the cornerstone of international efforts to achieve our long term goal of a world without nuclear weapons.

Our policy remains as set out in the 2015 Strategic Defence & Security Review. This said, "We would use our nuclear weapons only in extreme circumstances of self-defence, including the defence of our NATO Allies. While our resolve and capability to do so if necessary is beyond doubt, we will remain deliberately ambiguous about precisely when, how and at what scale we would contemplate their use, in order not to simplify the calculations of any potential aggressor". The Review also said that "The UK will not use or threaten to use, nuclear weapons against any Non-Nuclear Weapons State Party to the Treaty of the Non-Proliferation of Nuclear Weapons (NPT). This assurance does not apply to any state in material breach of those non-proliferation obligations." We will continue to keep our nuclear posture under review in the light of the international security environment and the actions of potential adversaries.