My Lords, I thank my noble friend for that reply. Does he agree that any missile defence system will have immense expenditure implications, with far-reaching consequences for our existing defence strategy introduced after the recent defence review? Therefore, does he also agree that it is absolutely essential that, before we drift into any commitment from which it may be increasingly difficult to extricate ourselves, there is a convincing threat analysis that demonstrates why such a system is necessary and could be effective? Does my noble friend agree that we must be clear about the consequences for arms control and disarmament, which must remain a cornerstone of global security? Is not terrorism, in its nuclear, biological and chemical dimensions, a much more immediate threat? Is that being addressed adequately?