Following Khrushchev's controversial claim that (pure) communism could be reached "within 20 years", the new Soviet leadership responded by fostering the concept of developed socialism. Brezhnev declared the onset of the era developed socialism in 1971 at the 24th Congress of the Communist Party of the Soviet Union. Developed socialism was described as socialism "attaining developed conditions", the result of "perfecting" the socialist society which had been created. In short, it would be just another stage in the development of communism. Developed socialism evolved into the Brezhnev regime's ideological cornerstone, and helped it to explain the situation of the Soviet Union. However, the theory of developed socialism also held that the Soviet Union had reached a state in development where it was crisis-free, and this proved to be incorrect. As a result, Yuri Andropov, Brezhnev's successor, initiated the de-Brezhnevisation of the Soviet Union during his short time in office, and introduced more realistic ideological theses. He did retain developed socialism as a part of the state ideology, however.