In Moscow, Andrei Dmitriyevich Sakharov, the Soviet physicist who helped build the USSR's first hydrogen bomb, is arrested after criticizing the Soviet military intervention in Afghanistan. Sakharov's concept of the "Layer Cake" bomb showed some promising results, but in late 1952 the Americans successfully detonated the world's first "super bomb." The Soviet team rushed to catch up, and settled on the same winning concept as the Americans--radiation implosion. Although Sakharov was decorated with numerous Soviet scientific honors for his achievement, he became increasingly concerned with the implications of the terrifying weapon. In 1957, his concern about the biological hazards of nuclear testing inspired him to write a damning article about the effects of low-level radiation, and called for the cessation of nuclear tests. Following the publication of his essay, Sakharov was fired from the weapons program and became a vocal advocate of human rights. In 1975, he was the first Soviet to win the Nobel Peace Prize. After he denounced the 1979 Soviet invasion of Afghanistan, Soviet authorities were quick to respond, exiling him to Gorky, where he lived in difficult conditions. In December 1986, Sakharov's exile ended when Soviet leader Mikhail Gorbachev invited him to return to Moscow. He was subsequently elected to the Congress of People's Deputies as a democratic reformer and appointed a member of the commission responsible for drafting a new Soviet constitution.