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*Nick Harvey:* To ask the Secretary of State for Defence (1) whether US personnel will be asked to participate in his Department's work on the Warhead Pre-Concept Working Group; 
(2) whether the Warhead Pre-Concept Working Group has considered options for /(a)/ agent defeat and /(b)/ other warhead modifications, as part of its work; 
(3) whether work emerging from the /(a)/ theoretical enhanced radiation and /(b)/ residual enhanced radiation weapon warhead concept have been examined as part of the work of the Warhead Pre-Concept Working Group; and whether personnel at AWE Aldermaston have been briefed on these or other advanced nuclear weapons concepts by their US counterparts in the last three years. 
*Mr. Hutton:* I refer the hon. Member to the answer my predecessor gave him on 28 November 2007, /Official Report, column/ 453W from which he will be aware that research is currently being undertaken in support of the detailed review described in paragraph 7-4 of the December 2006 White Paper: The Future of the United Kingdom's Nuclear Deterrent (Cmd 6994). This review, which was previously overseen by the Warhead Pre-Concept Working Group (WPCWG) is now being coordinated by the Atomic Weapons Establishment within their systems engineering management structure under the direction of the Ministry of Defence. It is examining both the optimum life of the UK's existing nuclear warhead stockpile and the range of replacement options that might be available to inform decisions on whether and how we may need to refurbish or replace the existing
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warhead likely to be necessary in the next Parliament. Some of the work included in this review is being undertaken in co-operation with the US and with the assistance of US personnel under the 1958 UK-US Agreement for Co-operation on the Uses of Atomic Energy for Mutual Defence Purposes.
I am withholding further details of this ongoing review and related discussions held with the US under the 1958 Mutual Defence Agreement in the interests of national security.