Having helped to develop the Soviet hydrogen bomb, he campaigned against nuclear proliferation and called for Soviet–American cooperation. He fought courageously for reform and human rights in the USSR, for which he was awarded the Nobel Peace Prize in 1975. His international reputation as a scientist kept him out of jail, but in 1980 he was banished to Gorky (Nizhni Novgorod) and kept under police surveillance. He was freed (1986) in the new spirit of glasnost, and at his death he was honoured in his own country as well as in the West.