Future planned expenditure on the nuclear deterrent will be subject to cost savings measures identified in the Strategic Defence and Security Review (SDSR). This includes expenditure on the Atomic Weapons Establishment (AWE) and the Future Submarine Programme. Release of further detail may prejudice the Ministry of Defence's (MOD) negotiating position with its commercial suppliers, and final savings figures will depend on detailed SDSR-related implementation. The MOD is, therefore, not prepared to release this financial information at this time.We expect, however, that the in-service costs of the UK's nuclear deterrent, which includes AWE's costs, will remain similar to those of the 2006 White Paper.The AWE costs associated with the Mk4A modification form part of the Nuclear Warhead Capability Sustainment Programme, which cannot be distinguished from the AWE management and operation costs.