At the critical plenum of the Central Committee in February 1937, which decided the fate of Nikolai Bukharin and Alexei Rykov, who had led the opposition to collectivisation, Postyshev continually jeered at them as they tried to defend themselves and voted for both men to be arrested and shot. But when Nikita Khrushchev delivered his 'Secret Speech' to the 20th Party congress in 1956, he said that during the same plenum, Postyshev protested about the recent arrest of a Ukraine-based Communist official named Karpov, whom he said had been wrongly accused of being a Trotskyite. In a sharp exchange, Stalin demanded "What are you, actually?" and
