Beginning in 1956, after Nikita Khrushchev denounced Stalin and Stalinism in the speech "On the Cult of Personality and its Consequences" (25 February 1956), the PRC and the USSR had progressively divergent interpretations of Marxist ideology; by 1961, their intractable differences of ideologic interpretation and praxis provoked the PRC's formal denunciation of Soviet communism as the work of "revisionist traitors" in the USSR. Among the Eastern bloc countries, the Sino-Soviet split was about who would lead the revolution for world communism, China or Russia, and to whom would the vanguard parties of the world turn for political advice, financial aid, and military assistance. In that vein, the USSR and the PRC competed for ideological leadership through the communist parties native to the countries in their spheres of influence.