§ Lord Balniel
asked the Secretary of State for Foreign Affairs what conditions to ensure verification are considered necessary by the British Government in seeking to extend the nuclear test ban treaty to cover underground testing.
§ Mr. Padley
Despite recent advances in seismic research it remains true, as is shown by the recent publication of the results of United Kingdom research, that underground nuclear tests cannot be positively identified by seismic means alone. All that the new seismic techniques can do is to eliminate a large proportion of earthquakes and so considerably reduce the number of underground events which may or may not be nuclear tests. In consequence, to provide an assurance that the terms of a comprehensive test ban treaty were being complied with and to deter cheating there would need to be some means of identifying nuclear tests underground, and this can only be by inspection on the spot. It would not, of course, be necessary to inspect the site of every unidentified event but only that 171W proportion which we think would be adequate to deter cheating and to provide a sufficient degree of assurance that no clandestine testing was being carried out.