Others have given you answers, I am trying to tell you that the whole framing of the question is completely wrong.

For one, you have to realize that Russia and Eastern Europe had emerged from feudal societies (where even the idea of a national identity did not exist, Belarus as an national identity literally only exists because of the Soviet Union) and the failures with the wider empires that were collapsing such as the Central Powers and the subsequent monarcho-fascist leadership that took place afterwards. You would have to research what the Soviet Union thought of the National Question, how this fits into the wider decolonization event that was taking place across the world, and class analysis of the ethnic minorities. This will require actual work in understanding history instead of being fed moralistic answers. The Soviet Union was not a paradise but was reacting to reactionary nationalism that was forming within these countries which was later proved in the 80s (Yugoslavia is a brilliant showcase) with counter-revolutions as a result of Imperialism.

The Soviet Union is completely open about the reasons for doing the deportations, you can either accept the logic or simply delcare that Stalin and the rest of the world proletariat was irrational or did it for the sake of cruelty.