203. Telegram From the Department of State to the Embassy in the Soviet Union1

79463. Subject: Presidential Letter on Nuclear Testing.

1. S—Entire text.

2. Embassy should deliver to MFA immediately following letter from President to General Secretary Gorbachev.2

Begin text

Dear Mr. General Secretary:

On December 23, 1985, I wrote to you about the important issue of nuclear testing.3 In that letter I explained why we believe that some level of nuclear testing will continue to be required for the foreseeable future, as long as nuclear weapons remain the key element of deterrence. I also emphasized that I saw no reason why our two nations could not begin a process of narrowing our differences on nuclear testing, at the same time that we sought progress in other arms control negotiating fora. I argued that if we were successful in addressing the relevant verification concerns of both sides, we could move toward ratification of the Threshold Test Ban Treaty (TTBT) and the Peaceful Nuclear Explosions Treaty (PNET) and lay the basis for further consideration of nuclear testing issues.

My views on the need to begin a dialogue on nuclear testing limitation have not changed. As you know, we are seriously concerned with the pattern of your testing and have determined that a number of your tests constitute likely violations of your obligation to observe the TTBT threshold. For your part, you have also raised questions about the yields of particular U.S. tests. I can assure you that all our tests have been below the 150 kiloton threshold. But you should not have to take my word for it; you should be able to verify it for yourself. And that is exactly why I have proposed that our experts meet to discuss resolution of our differences on this issue.

As I have said in previous letters, what we have in mind is a process in which we can build a basis for confidence on both sides at [Page 862] every stage. As an indication of our readiness to build that basis I would like to propose that we agree on the following steps as a means of moving toward ratification of the TTBT.

Our scientists tell me that the best way of reducing uncertainties in verifying compliance with the 150 kiloton threshold is by using a method called CORRTEX—an on-site hydrodynamic yield measurement technique that measures the propagation of the underground shock wave from a nuclear explosion. If we could reach agreement on the use of an effective verification system incorporating such a method to verify the TTBT, I would be prepared to move forward on ratification of both the TTBT and the PNET, and you could do the same.

I believe the CORRTEX method provides a reasonable technique of measuring the yield of nuclear tests without compromising essential national security information on either side. Using the CORRTEX method, a coaxial cable is placed in a hole parallel to that containing the nuclear device being tested. When the nuclear device is detonated, a shock wave emanates through the ground crushing and shortening the cable. The rate at which the cable length changes is recorded via measurements of the rate of changing electronic pulse. This rate is a measure of the propagation of the explosive shock wave through the ground which is in turn a measure of the yield of the nuclear explosion. Our scientists believe that, on the basis of our extensive experience, CORRTEX has been shown to be accurate to within 30 percent of more direct radio-chemical yield measurements for tests of greater than 50 kilotons.

To allow you to examine the CORRTEX system more fully, I propose that you send your scientists to our test site during the third week of April, 1986. At that time they could also monitor a planned U.S. nuclear weapons test. I would hope this would provide an opportunity for our experts to discuss verification methods and thus pave the way for ratification of the TTBT and PNET.

I have tried to be as specific as possible in outlining what we have in mind for this important step in the process of limiting nuclear explosions. I look forward to hearing from you soon on our concrete proposal. We stand ready to facilitate in every way the visit of your experts to our test site. I hope this can be the start of a productive dialogue on resolving our differences on the nuclear testing issue.

In closing, I would like to return to the subject of risk reduction centers which we agreed in Geneva to explore. Our mutual efforts to have experts meet and discuss the concept have not been successful to date. Perhaps at the time your experts are involved with ours at the Nevada test site, we could have another group of experts meet at a place of your choosing to explore the contributions that centers such as these could make to our mutual security. For our part, we will be [Page 863] prepared to present our ideas on possible functions for risk reduction centers and the benefits we can both derive from such activity.


Ronald Reagan

End text.

  1. Source: Department of State, Central Foreign Policy File, Electronic Telegrams, N860003–0301. Secret; Niact Immediate; Nodis. Drafted from text received from the White House; cleared by Ridgway, Timbie, and Andres; approved by Bova.
  2. In telegram 4408 from Moscow, March 15, the Embassy reported the Political Counselor delivered the letter to the Ministry of Foreign Affairs on March 15. (Department of State, Central Foreign Policy File, Electronic Telegrams, N860003–0320)
  3. See footnote 5, Document 177.