More than fifty years ago, human beings faced the gravest nuclear escalation in world history. From early summer 1961, the Soviet Union started to challenge the United States on many fronts: The Soviets built a wall that divided Berlin, thus transforming that city into a symbol of the cold war itself. Furthermore, the Soviets were improving their intercontinental ballistic missiles system by testing a long-range missile named R-9 Desna—or SS-8 Sasin as NATO reports called it. As part of this escalation strategy, they decided to resume their atmospheric nuclear testing program by late summer of that year. At that point, the American administration had to decide whether and how to reply to the systematic and increasing Soviet threats. This essay tries to explain to what extent Kennedy's administration was shattered by a combination of uneasiness and anxiety in dealing with the choice to resume atmospheric nuclear tests. While the administration was pressured by strategists, military elites, and nuclear hard-liners who called for a bold reply to the USSR's provocations, the administration also had to contend with an internal public opinion that was reluctant to passively accept the resumption of American tests. Indeed, many Americans, who were scared by nuclear fallout, had been educated, coordinated, and organized by several private and influential anti-nuclear groups. These groups took the lead in protesting and eventually increased the general awareness of nuclear testing. Consequently, as recently disclosed documents seem to confirm, this essay considers Kennedy's choice as a particularly complex one. Rhetorically, ideologically, and strategically, the choice to delay and limit the U.S. nuclear program ultimately meant the end of an era and the advent of the détente.