In 1969, Enrico Berlinguer, PCI deputy national secretary and later secretary general, took part in the international conference of the Communist parties in Moscow, where his delegation disagreed with the "official" political line and refused to support the final report. Unexpectedly to his hosts, his speech challenged the Communist leadership in Moscow. He refused to "excommunicate" the Chinese Communists and directly told Leonid Brezhnev that the invasion of Czechoslovakia by the Warsaw Pact countries (which he called the "tragedy in Prague") had made clear the considerable differences within the communist movement on fundamental questions such as national sovereignty, socialist democracy and the freedom of culture. At the time the PCI, which had absorbed the PSI's left-wing, the Italian Socialist Party of Proletarian Unity, so strengthening its leadership over the Italian left, was the largest communist party in a capitalist state, garnering 34.4% of the vote in the 1976 general election.