A primary preoccupation of Soviet foreign policy since World War II has been the control of Eastern Europe. Eastern Europe has been important to the USSR for several reasons: the military security factor, the springboard factor, the communist internationalist factor, and the ideological security factor. Soviet policy toward Eastern Europe has differed importantly in the Khrushchev and the Brezhnev eras. After 1956, following Stalin's attempt to achieve total control of the area, Khrushchev sought to find the right combination of cohesion and viability in Eastern Europe. Khrushchev was willing to experiment with departures from Stalinist conformity in quest of a viability that postulated making the Communist system in Eastern Europe more legitimate. Consequently, East European states were able to assert distinctive policies, domestically and internationally. The most notable reform measures of the Khrushchev era were those affecting economic structure, planning, and policy. These economic reforms had political consequences; departures from the old command system of economy tended to encourage pluralism in other branches of public life. After Khrushchev's ouster in 1964, these developments gathered a momentum of their own. Powerful forces of nationalism and sociopolitical challenge to Communist Party absolutism were unleashed. Earlier, the Albanian leadership had taken advantage of the Sino-Soviet dispute to remove Albania from the Soviet orbit. In Rumania, national autonomy was developed into nationalist Rumanian policy through skillful manipulation of the Sino-Soviet dispute and other factors.