Effectiveness of nuclear test detection system

The document discusses the effectiveness of the nuclear test detection system. It states that the detection of underground tests is more certain as long as the yield is above 20 kilotons (KT). However, the probability of detecting tests with yields lower than 11 KT is quite small. If the height of burst is increased to altitudes above 30,000 feet, it becomes difficult to prove that the acoustic signals picked up are from nuclear tests. The United States' detection system is primarily focused on tests in the Northern Hemisphere, but conventional intelligence may provide indications of Soviet tests in the Southern Hemisphere.

There is some uncertainty regarding the effectiveness of the test detection system, as evidenced by discussions in a previous meeting. Technical limitations and the difficulty of accurately measuring fission products in the atmosphere make it challenging to enforce test limitations or detect violations.

In summary, the document concludes that the United States is reasonably certain of detecting Soviet tests above 20 KT, but the Soviets cannot covertly conduct tests with yields greater than 5 KT with a high degree of assurance.