Greetings Historians. I can appreciate in the context of the Cold War that there was a political component to nuclear testing. Is there any known purpose behind this lull?
Edit: if I had to guess, it was a sign of good faith in negotiating the 1963 partial test ban treaty, but I have no evidence of this.
The period of 1958-1961 was known as the Test Ban Moratorium. It was a voluntary agreement between the USA, UK, and USSR not to test nuclear weapons. (At the time it started, they were the only states with nuclear weapons. The French tested their first bomb in 1960, the Chinese in 1964.) In the fall of 1961, the Soviets announced they were going to begin testing again, which ended the Moratorium. You can read about the various political factors that went into it, and how it played a role in what became the Limited Test Ban Treaty in 1963, here. It was more than a good faith aspect; it was a deliberate attempt to slow arms development, at least temporarily. If you don't test nukes, it is hard to innovate them.