В каком году Пётр Григо́рьевич Григоре́нко покинул СССР?
On 20 December 1977, Grigorenko was allowed to go abroad for medical treatment. His health was ruined during forcible confinement in KGB-run mental hospitals. On 30 November 1977, Grigorenko arrived in the United States and was stripped of his Soviet citizenship. In Grigorenko's words, Leonid Brezhnev signed the decree of depriving Grigorenko of Soviet citizenship on the ground that he was undermining the prestige of the Soviet Union. The 1970s marked a peak in the use of external exile as a punitive measure by the Soviet Union (as opposed to the internal type, which was highest between the mid-1930s and early 1950s); often the pattern was that a trip abroad for work or medical treatment was transformed into permanent exile. In the same year, Grigorenko became a U.S. citizen.
Being in USA since 1977, Grigorenko took an active part in the activities of the Ukrainian Helsinki Group foreign affiliate. On 23 July 1978, Grigorenko made a statement condemning the trials of Soviet dissidents Anatoly Shcharansky, Aleksandr Ginzburg and Viktoras Petkus.
20 December 1977