Stalin used russian chauvinism. When he was at the head of the USSR, appeared the idea that russian people was "the grand-brother" among over soviets peoples, idea that was fought in the 20s. From 30s to 50s, even in the federate republics of Caucasus and Central Asia, most important positions (directions of police and KGB, for example) were systematically held by Russians (or, in a lesser measure, by Ukrainians and Belarussians).