During the cordial Sino-Soviet relations of the 1950s, the USSR engaged in a cooperative technology transfer program with the PRC under which they trained Chinese students and provided the fledgling program with a sample R-2 rocket. But when Soviet premier Nikita Khrushchev was denounced as revisionist, with Mao asserting that there had been a counter-revolution in the Soviet Union and that capitalism had been restored, the friendly relationship between the two countries turned to confrontation. As a consequence, all Soviet technological assistance was abruptly withdrawn after the 1960 Sino-Soviet split.