Foreign Relations of the United States, 1961–1963, Volume VII, Arms Control and Disarmament

156. Message From Prime Minister Macmillan to President Kennedy⁰

London, March 14, 1962.

Dear Friend, As I promised in my message of March 13,¹ I am now in a position to send you my further thoughts elaborating the proposals made in the latter half of my message of March 9.² I am very glad that you feel able to accept our scientific team in Washington at the end of this week, when they will be able to discuss the scientific assessment with your people.³

Our United Kingdom scientists believe that they have made important improvements to instrumentation and they believe that substantial amounts of information could now be obtained from seismic measurements at distances of about 1,500 to 2,000 miles from an underground explosion. This would be in what I understand is called the third seismic zone and remoter areas. The British scientists are therefore considering urgently the technical aspects of a detection and location system which would be manned only by the nationals of the country in which the posts were situated. This suggestion requires a full technical appreciation of the possibilities of detection and accurate location from measurements in the third zone and beyond. The data which we have obtained causes us to think that the conclusions derived, both as regards detection and location, are much less influenced by anomalies in the geology of the test site than are those in the first zone. No doubt you have a great deal of data relating to the third zone and beyond which you will have derived from the recent shots in Nevada and our scientists would be particularly interested to test their ideas against these data. We believe that from measurements in the third zone and beyond we can locate an event within a radius of better than five miles. This would mean pin-pointing the event in an area of something less than 75 square miles. We recognize, however, that it may be more difficult to diagnose whether the event was natural or an explosion if the measurements are only made from these distant stations. We therefore believe that if the West is to rely on measurements made from outside Russia in monitoring a test ban, more inspections may be necessary than if the original Geneva ideas were followed. This is, of course, on the basis that if either side attempted a violation, they would try to falsify records from stations under their control.

If our fall-back position proves to be of a nature which does require more inspections within the U.S.S.R. than the original Geneva proposals, we may have to consider whether there are any possible further modifications on the political or administrative side which would make the inspections more acceptable to the Russians. There are two possible modifications which might be worth further thought—

(a) The composition of inspection teams

We might consider adding a neutral element to the United States/United Kingdom teams which, under our present draft treaty text, verify doubtful events in the U.S.S.R. This is, I know, not wholly a new proposal, since we put forward ideas on these lines at Geneva last August when the Russians ignored them.

(b) Our right to demand inspections

So far, we have said that inspections in the U.S.S.R., whether within our quota or on a sliding scale above it, should all take place at our own demand. If the total number of inspections is likely to be increased, we might think of a fixed quota of inspections at our request, for which we would ask, plus a sliding scale of further inspections, in proportion to doubtful events, each to take place at the request, not of ourselves, but the majority of the Control Commission.

Both these points would need further detailed consultation, but it seems to me that we should be able to make an offer on them which looked reasonable but did not endanger our essential position.

I see from the preliminary reports from Geneva that you may have doubts about the reliability of detection posts outside United States/United Kingdom territory. This is, of course, a point of serious examination. But if we were to move to a national detection system, we could presumably overtly increase the existing number of stations by general agreement. As a check, we might consider continuing some covert stations of our own, on the present pattern. We would certainly be prepared to examine whether there are any new areas where the United Kingdom could profitably help. And if the national stations were overt it seems to me that the risk of disturbances to them because of a change of regime would be much less great.

In the penultimate paragraph of my message of March 9, I suggested that the Russians would need a series of tests if they were to cheat for any worthwhile purpose. A single 100-kiloton shot could not possibly provide the basis for any sort of breakthrough. This could only be given by a series of shots; I am advised that the very least would be one or more low-kiloton shots, followed by one with a yield in the megaton range. Even then, it is really only development of a successful anti-missile-missile that could seriously disturb the validity of the deterrent. Even such a development would have more of an effect in principle than in practice, since I believe that the construction and deployment of a defence system likely to reduce the scale of damage to a supportable level would be so vast as to be beyond Soviet capacity.

The more I think about this, the more I feel certain that we cannot afford to let the hopes of the world for a nuclear test ban be dashed at Geneva without a further public effort which would be demonstrably fair and will catch the imagination. Of course, if the Russians are forced finally to a position in which they refuse all form of inspection on their territory then we shall fail, but if we can get them into this position, we should have world opinion on our side.

With warm regard,

Yours ever,

Harold Macmillan⁴

0. Source: Department of State, Presidential Correspondence: Lot 66 D 204, M-K, 1961-1962. Top Secret.
1. President Kennedy suggested in a March 10 message to Macmillan that British and U.S. scientific experts convene in Washington to exchange views on the status of scientific data regarding detection of underground seismic data. (Ibid., K-M, 1961-1962) In accepting the invitation in his March 13 letter to President Kennedy, Macmillan proposed to send a junior group of experts on March 14 to be followed by Sir William Penney and Sir Solly Zuckerman. (Ibid., M-K, 1961-1962) For text of both letters, see the Supplement.
2. In his March 9 message to Kennedy, Macmillan wrote that if it could be justified by the scientists, “we might accept a much simpler treaty based on national detection systems alone, but with the very important proviso that these shall be supported by an international authority (as provided for in our 1961 treaty) but responsible in the main for two primary functions.” These two functions were: “(i) to collate and evaluate seismic data from all over the world, and (ii) to have under its control mobile inspection teams, who could be sent to investigate without hindrance any suspected violation of the treaty in any country.” Macmillan believed that the latest British scientific advice seemed to suggest that this would give acceptable coverage, and he hoped U.S. and British scientists might be able to come to “a rapid joint assessment” on the question. (Department of State, Presidential Correspondence: Lot 66 D 204, M-K, 1961-1962) See the Supplement.
3. British scientists headed by Sir Solly Zuckerman met with their U.S. counterparts in Washington March 17-18; see Document 159.
4. Printed from a copy that bears this typed signature.