to activism Since the late 1950s Sakharov had become concerned about the moral and political implications of his work. Politically active during the 1960s, Sakharov was against nuclear proliferation. Pushing for the end of atmospheric tests, he played a role in the 1963 Partial Test Ban Treaty, signed in Moscow. Sakharov was also involved in an event with political consequences in 1964, when the Soviet Academy of Sciences nominated for full membership Nikolai Nuzhdin, a follower of Trofim Lysenko (initiator of the Stalin-supported anti-genetics campaign Lysenkoism). Contrary to normal practice, Sakharov, a member of the academy, publicly spoke out against full membership for Nuzhdin and held him responsible for "the defamation, firing, arrest, even death, of many genuine scientists." In the end, Nuzhdin was not elected, but the episode prompted Nikita Khrushchev to order the KGB to gather compromising material on Sakharov. The major turn in Sakharov's political evolution came in 1967, when anti-ballistic missile defense became a key issue in US–Soviet relations. In a secret detailed letter to the Soviet leadership of July 21, 1967, Sakharov explained the need to "take the Americans at their word" and accept their proposal for a "bilateral rejection by the USA and the Soviet Union of the development of antiballistic missile defense" because an arms race in the new technology would otherwise increase the likelihood of nuclear war. He also asked permission to publish his manuscript, which accompanied the letter, in a newspaper to explain the dangers posed by that kind of defense. The government ignored his letter and refused to let him initiate a public discussion of ABMs in the Soviet press. Since 1967, after the Six Day War and the beginning of the Arab-Israeli conflict, he actively supported Israel, as he reported more than once in the press, and also maintained friendly relations with refuseniks who later made aliyah. In May 1968, Sakharov completed an essay, "Reflections on Progress, Peaceful Coexistence, and Intellectual Freedom". He described the anti-ballistic missile defense as a major threat of world nuclear war. After the essay was circulated in samizdat and then published outside the Soviet Union, Sakharov was banned from conducting any military-related research and returned to FIAN to study fundamental theoretical physics. For 12 years, until his exile to Gorky (Nizhny Novgorod) in January 1980, Sakharov assumed the role of a widely recognized and open dissident in Moscow. He stood vigil outside closed courtrooms,