My Lords, we recognise that the complete elimination of nuclear weapons will require extremely rigorous verification requirements in order to provide a high level of assurance against cheating. It is certainly true that major challenges arise in seeking to develop such verification arrangements. However, we do not accept that the challenges are insurmountable. Indeed, following the 1998 Strategic Defence Review, the Government set in hand a programme to develop expertise in that very area, drawing in particular on our own specialist expertise at the Atomic Weapons Research Establishment. The initial results of that work were warmly welcomed by the other states at the recent NPT Review Conference and it has now been taken further.