Of course one of the results of the accident which I had described before, and the general fear connected with nuclear explosives, led to negotiations to limit testing. I had doubts about that. I felt - I still feel - that knowledge obtained by testing, if done carefully enough, should not be eliminated. But the situation in the late '50s, in the early '60s, was a strong movement toward elimination of testing and there was actual ban on testing for a two or three year period around 1960. The story about that is that this ban was eventually and rapidly broken by the Soviets who started to test again using a very big explosion - I think the biggest ever actually fired, 100 megatons, approximately five thousand times that of Hiroshima. It became quite evident that while we were not testing we were under instructions essentially to slow down or stop all progress in that direction whereas the Soviets had prepared for a test series. The result in the early 1960s was many more and more effective tests by the Soviets than by ourselves and the result was that at that time the Soviets effectively managed to catch up with American nuclear technology, explosive technology, to the extent that that was possible, or that is verifiable. In the meantime however Livermore had made a very important specific change. A new type of explosion, not in the atmosphere, but underground.