From 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. In 1965 he returned to fundamental science and began working on
cosmology but continued to oppose political discrimination.
The major turn in Sakharov’s political evolution started 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 explains 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 otherwise an arms race in this new technology would 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 this kind of defense. The government ignored his letter and refused to let him initiate a public discussion of ABM in the Soviet press.
In May 1968 he completed an essay,
Reflections on Progress, Peaceful Coexistence, and Intellectual Freedom, where the anti-ballistic missile defense is featured as a major threat of world nuclear war. After this essay was circulated in
samizdat and then published outside the Soviet Union, Sakharov was banned from all military-related research and Sakharov returned to FIAN to study fundamental theoretical physics. In 1970 he, along with
Valery Chalidze and
Andrei Tverdokhlebov, was one of the founders of the
Moscow Human Rights Committee and came under increasing pressure from the regime. He married a fellow human rights activist,
Yelena Bonner, in 1972.
In 1973 he was nominated for the
Nobel Peace Prize and in 1974 was awarded the
Prix mondial Cino Del Duca. He was awarded the Nobel prize in 1975, although he was not allowed to leave the Soviet Union to collect it. His wife read his speech at the acceptance ceremony.
Sakharov's ideas on social development led him to put forward the principle of human rights as a new basis of all politics. In his works he declared that "the principle 'what is not prohibited is allowed' should be understood literally", denying the importance and validity of all moral or cultural norms not codified in the laws. He was arrested on
January 22 1980, following his public protests against the
Soviet Invasion of Afghanistan in 1979 and was sent to
internal exile in the city of
Gorky, now
Nizhny Novgorod, a
closed city that was inaccessible to foreign observers.
Between 1980 to 1986, Sakharov was kept under tight Soviet police surveillance. In his memoirs he mentions that their apartment in Gorky was repeatedly subjected to searches and heists. He remained isolated but unrepentant until December 1986 when he was allowed to return to Moscow as
Mikhail Gorbachev initiated the policies of
perestroika and
glasnost.
In 1988 Sakharov was given the International Humanist Award by the
International Humanist and Ethical Union.
He helped to initiate the first independent legal political organizations and became prominent in the Soviet Union's growing political opposition. In March 1989, Sakharov was elected to the new parliament, the
All-Union Congress of People's Deputies and co-led the democratic opposition.
Soon after 9:00 pm on December 14, 1989, Sakharov went to his study to take a nap before preparing an important speech he was to deliver the next day in the Congress. His wife went to wake him at 11:00 pm as he had requested but she found Sakharov dead on the floor. A sudden
heart attack had taken his life at the age of 68. He was interred in the
Vostryakovskoye Cemetery in Moscow.