What was Stalin’s position on the unification of the USSR into a single society and national policy?

During the leadership of the country, V. Lenin proposed to unite the republics on a sovereign basis. At the same time, they had to have the possibility of self-determination. Stalin pursued the opposite policy. It consisted in uniting the state into a union with complete dependence on the center. National minorities in some situations lost the ability to follow their direction in relation to some issues. Citizenship was introduced unified. At the same time, the nationality could be indicated in the passport of a citizen of the USSR.