Details of nuclear warhead convoys are kept secret by the UK government and the MoD who operate a "Neither Confirm Nor Deny" policy on informing the public regarding convoys. Evidence given by the Nuclear Information Campaign to the Defence Select Committee (based on figures from campaign group Nukewatch UK for 2000 to 2006) give the number of convoys as ranging from two to six return journeys per year from Aldermaston to Coulport. Estimates of the warhead numbers transported during this period are that 88 were moved from Aldermaston to Coulport while 120 were returned, indicating a withdrawal of between 30 and 50 warheads leaving an operational stockpile of between 170 and 150 warheads.