As part of his statement on the Strategic Defence and Security Review (SDSR) on 19 October 2010, my right hon. Friend the Prime Minister announced that we had reviewed our nuclear deterrence requirements. He concluded that we could deliver a credible nuclear deterrent with a smaller nuclear weapons capability and would incorporate these reductions into the current deployed capability and the future successor deterrent programme. The number of deployed warheads on each submarine would be reduced from 48 to 40; the number of operational missiles in the VANGUARD-class ballistic missile submarines (SSBN) would be reduced to no more than eight; and we would reduce the number of operationally available warheads from fewer than 160 to no more than 120.
The then Secretary of State for Defence, my right hon. Friend the Member for North Somerset (Liam Fox), announced to the House on 29 June 2011 that the programme for implementing the 2010 SDSR warhead reductions had commenced.
I am pleased to inform the House that this Government has now met its commitment to implement these changes across the SSBN fleet. All Vanguard Class SSBNs on continuous at-sea deterrent patrol now carry 40 nuclear warheads and no more than eight operational missiles. We have therefore achieved our commitment to reduce the number of operationally available warheads to no more than 120.
The nuclear deterrent remains to serve as the ultimate means to deter the most extreme threats. The Government continues to plan to renew the UK’s independent strategic nuclear deterrent, though the Liberal Democrats will continue to make the case for alternatives. A “Main Gate” investment decision will be required in 2016 to replace the four Vanguard Class SSBNs currently in service. At the same time, as a responsible nuclear weapon state and party to the Treaty on the Non Proliferation of Nuclear Weapons (NPT) the UK remains committed to creating the conditions for a world without nuclear weapons.
The completion of these reductions is a key milestone, demonstrating the UK’s continued leadership within the NPT.