asked Her Majesty's Government:Whether in their view the underground nuclear test carried out by the Soviet Government on or about 14th September 1980 did or did not exceed the limit of 150 kilotons established in the 1974 Agreement between the Soviet Union and the United States and, if so, by how much.

The data available on this test do not permit a precise conclusion as to whether or not it exceeded 150 kilotons. Our assessment is that the yield was probably about 150 kilotons.