Foreign Relations of the United States, 1977–1980, Volume XXVI, Arms Control and Nonproliferation

158. Memorandum From the Acting Director of the Arms Control and Disarmament Agency (Keeny) to the President’s Assistant for National Security Affairs (Brzezinski)¹

Washington, May 18, 1977

SUBJECT

• The Meaning of “Yield” in the Treaty on the Limitation of Underground Nuclear Weapon Tests

The May 9, 1977² letter to you from the Acting Administrator of ERDA regarding the review of U.S. testing policy recommended by Mr. Warnke in his memorandum of April 29, 1977³ raises a number of questions which should be part of the recommended review, and on which ACDA will defer further comment at this time.

The ERDA letter also raises a serious question as to whether there is agreement between the United States and the Soviet Union on the meaning of “yield” in the Treaty on the Limitation of Underground Nuclear Weapon Tests. The letter implies that an understanding exists between the United States and the Soviet Union on the meaning of “yield” to the effect that the United States would draw no distinction between “design” and “actual” yield. This Agency is unaware of any communication by the United States to the Soviet Union or of any agreement between the United States and the Soviet Union on this subject.

The question of the definition of yield will presumably become public during the pending Senate ratification hearings on this Treaty. If the Soviet Union were to challenge the proposed “design” yield definition, the United States could find itself in an embarrassing position since the ordinary meaning of the term “yield” in the Treaty context would appear to be “actual” yield.

Spurgeon M. Keeny, Jr.
Acting

1. Source: Washington National Records Center, OSD Files: FRC 330–80–0017, Box 63, A–400.112 1977. Secret. Copies sent to Vance, Harold Brown, Lance, George Brown, and Turner.
2. See Document 156.
3. See Document 154.