My Lords, there will be no drift at all into such a defence system. Perhaps I may quote from the SDR published some three years ago. It states that systems,

"may play a role within a balanced spectrum of capabilities to counter the risks posed by chemical and biological weapons and their means of delivery. But technologies in this area are changing rapidly and it would, at this stage, be premature to decide on acquiring such a capability".

It went on to say:

"We will, however, monitor developments in the risks posed by ballistic missiles and in the technology available to counter them, participate in NATO studies, and work closely with our Allies to inform future decisions".

That was two or three years ago and it is exactly the policy that we have followed since then. What we said then applies now. Of course, my noble friend is right that any system would be very expensive. As far as disarmament is concerned, the goal of Her Majesty's Government is the global elimination of nuclear weapons. That remains our policy.