105. Memorandum from Brown to McNamara, March 201

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  • Joint US–UK Technical Discussions on Nuclear Test Ban Questions

At the urgent request of Prime Minister MacMillan a group of British scientists led by Sir Solly Zuckerman met with U.S. scientists on Saturday and Sunday, March 17–18. The stated purpose of the meeting was to reach an agreed position on the scientific aspects of nuclear test ban control.

The meeting was a meandering affair touching on numerous scientific questions. It appeared to DOD representatives present, however, that the principal matter of interest to the British was the adequacy of national or unilateral seismic detection systems to monitor an underground test ban agreement. The simplest interpretation of British intent is that they are seeking scientific support for a proposal of a test ban agreement without international controls of the sort which the U.S. has always considered necessary.

In the course of the meeting no technical results were presented by either the U.K. or U.S. scientists to indicate that the problems of underground test detection had been solved.

A decision at this time to enter into a test ban agreement with only national systems for control would be a purely political decision, not warranted by any change of the technical situation.

I recommend that you oppose any move in this direction, in view of:

(a) the continuing need to prevent an imbalance in nuclear weapons development. Though underground testing is limiting, it does allow gains and could be hidden without inspection as a safeguard.

(b) the very bad precedent any treaty based on national systems would set for future disarmament agreements.

Harold Brown
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1. That Western unilateral detection systems can currently detect seismic events in the USSR of magnitude 4.75 or slightly less. This will lead on the average to detection of about 125 shallow seismic events per year within the USSR.

2. That the proposed Geneva system is predicted to detect seismic events down to 3.75 magnitude, which implies detection of about 1,000 shallow events per year in the USSR. This system could not be available much before 1965.

3. That improvements of detection by unilateral systems to perhaps magnitude 4.2 in the USSR is a reasonable technical goal for 1965. This, we now believe, implies detection of 300 shallow seismic events per year within the USSR. Among the research areas of particular promise are use of deep hole detection systems and correlation of [Facsimile Page 3] data from phased arrays.

4. That a unilateral system can currently locate detected seismic events to within a radius of from 10 to 20 km.

5. That, with utilization of data from an improved internal USSR seismic detection system for the purpose of calibrating the external system, the location capability of an external unilateral system might improve to the point where location to within a radius of ten km. or less in seismic areas would be feasible. This conclusion is predicated on the assumption that the USSR data are not falsified.

6. That at present it is impossible unilaterally to identify shallow seismic events in the USSR as earthquakes, excepting at large magnitudes, but that future improvements, in particular ones involving processing of data from large arrays, offer hope of reducing the magnitude at which identification of some earthquakes is possible down to about magnitude five. There does not appear [Facsimile Page 4] to be any prospect of identifying a given event as an explosion by seismic means alone.

7. That if a unilateral system (for example a non-Soviet system for detecting events within the USSR) is to be used as a basis for initiating inspections, it will be necessary to agree on objective criteria which will determine eligibility for inspection and to establish a mechanism for certifying the eligibility of a given event. Although these problems were discussed no specific proposals have been formulated.

  1. Joint U.S.–U.K. technical discussions on nuclear test ban questions. Attached is a draft of the agreed conclusions of U.S–U.K. discussions. Secret. 4 pp. Washington National Records Center, RG 330, OSD Files: FRC 66 A 3542, Atomic 000.01–400.112, 1962, Box 57.