Final answer:
Under Joseph Stalin, the Soviet Union underwent a shift towards totalitarianism and centralization of power. Stalin established a police state, suppressed political opposition, and took control of the economy.
Step-by-step explanation:
Under Joseph Stalin, the Soviet Union shifted towards totalitarianism and centralization of power. Stalin established a powerful police state that monitored all aspects of Soviet life, using terror and intimidation to enforce his policies. He promoted communism through education and extensive propaganda, while suppressing political opposition through arrests and executions. Stalin also took control of the Soviet economy through a series of economic plans that modernized the country.