I can answer the second part of your question, what was the justification for Stalinist-era Soviet ethnic policies. It seems counterintuitive that a society built on Marxism would promote nationalism. After all, Marx and Engels believed that nationalism was a product of capitalism and would wither away with the state during the transition to communism^1. However, Marx and early Marxists realized that nationalism was useful and supported it when they thought it would advance their political vision, for example during the Revolutions of 1848^2.

In the Soviet Union under Stalin, there is a similar blend of ideology and political pragmatism when approaching nationality. In essence, nationalism was useful until it wasn’t. The policy pursued under Stalin’s leadership was to create an international brotherhood of national communist parties, which was based on Stalin’s own belief that the international communist movement should be combined with nationalism^3. Stalin had been the party’s expert of nationalities in the 1910s to early 1920s, and then he believed that “nationalism was a distraction from the cause of socialism.”^4 This would change during World War II. As the Comintern leader Georgi Dimitrov wrote, Stalin felt then that their postwar goal would be “to develop the idea of combining a healthy, properly understood nationalism with proletarian internationalism. Proletarian inter[nationalism] should be grounded in such a nationalism in the individual countries.”^5 Stalin felt that “national feelings and the notion of a homeland” would lead to cooperation, while “rootless cosmopolitanism” would create spies.

The reason I said that nationalism was useful until it wasn’t is that nationality was a means to an end, and if it no longer led to that end then it could be seen as a threat. The famines that took place in Ukraine and Kazakhstan during 1932-1933 were a result of many direct policies from Moscow, including Stalin’s fear of Ukrainian nationalism which he felt could pose an existential threat to the Soviet project^6. This was in part due to the Ukrainian nationalist movements and peasant revolts that had posed serious challenges for the Bolsheviks during the Russian Civil War, as well as Stalin’s fear of a Polish-Japanese alliance which he thought might take advantage of Ukrainian opposition in the event of an invasion^7.

In Eastern Europe after World War II, the Soviets saw nationalism as a way to establish legitimacy. The introduction to The Communist Quest for National Legitimacy , ed. Martin Mevius lays out a decent literature review of work on nationalism under communism, but it is still a growing area of study. What is becoming apparent is that nationalism was employed much more frequently than is typically assumed in the Eastern Bloc. For example, in Czechoslovakia the communists were successfully able to gain significant public support before the 1948 coup d'etat in part because under Klement Gottwald they made a deliberate effort to be the most nationalist party^8. The ethnic cleansing of Germans that took place in the former Sudetenland as well as in Poland were not policies started by the communists, but in both countries the communists were able to take advantage of nationalist and anti-German sentiments and the land redistribution policies that came with that to claim legitimacy.

1 - Karl Marx and Friedrick Engels, Economic and Philosophical Manuscripts

2 - Michal Kasprzak, “To reject or not to reject nationalism: debating Marx and Engels’ Struggle with Nationalism, 1840s-1880s,” 2012.

3 - Jan Berends, “Nation and Empire: Dilemmas of Legitimacy During Stalinism in Poland,” 2009.

4 - Anne Applebaum, Red Famine , 2017, p25.

5 - Georgi Dimitrov, quoted in Jan Berends, “Nation and Empire: Dilemmas of Legitimacy During Stalinism in Poland,” 2009.

6 - Applebaum, 2017, 428.

7 - Timothy Snyder, Bloodlands , 2010.

8 - Chad Bryant, Prague in Black , 2007.

The film Tsirk ("Circus" in Russian) is a famous piece of Soviet propaganda from 1938 about the ethnic inclusivity of the U.S.S.R. Here is its famous international lullaby, where individuals of many Russian ethnic groups sing in their own languages to a mixed race (half-African American, half-white) child in a mass show of acceptance. However, the verses sung in Yiddish by Solomon Mikhoels were soon removed, and the singer, who was appointed chairman of the Jewish Anti-Fascist Committee upon its founding in 1941, was assassinated on the order of Stalin in 1948.

The book Sound, Speech, Music in Soviet and Post-Soviet Cinema by Lilya Kaganovsky and Masha Salazkina describes this interesting paradox. The Soviet Union positioned itself as "the ideological home of the international proletariat"... but the official state language was Russian (page 126). The Caucasus (Armenia, Azerbaijan, Georgia), Baltic states (Estonia, Latvia, Lithuania), and other ethnic minority countries were the "younger brothers" to the great "elder brother" of Russia.

Here are examples of Soviet propaganda posters which emphasize the inclusivity of the Soviet Communist state, and particularly contrasted the racist attitudes against African American and Chinese communities in America. The Soviet Union distinguished itself as superior to the West in many ways, but one of those ways was its tolerance and even rejoice of other ethnicities.

"China Express", aka "The Blue Express" in the original Russian title, was a U.S.S.R. movie from 1929 which depicted the bourgeoisie vs. proletariat struggles that China was experiencing. It was notable as a depiction of POC without overt racial stereotyping, and many of the actors were ethnically Chinese.

In the 1920's, African American/Harlem Renaissance jazz musicians were welcomed into the U.S.S.R. Many went on tours through the Soviet Union and then decided to stay, hoping to experience a life of equality and prosperity unlike what they experienced in the U.S.

However, this welcoming and tolerant image that the U.S.S.R. projected for itself in the 1920's and early 1930's soon gave way to censorship of non-Russian, non-Soviet culture. Jazz was banned as an example of bourgeois Western culture in the late 1930's.

The book Ethnic Cleansing in the USSR, 1937-1949 by J. Otto Pohl shows the attitude that the U.S.S.R. began to have toward ethnic minorities. "Immigrants to the USSR...who [Stalin] feared...were filled with spies and saboteurs awaiting orders from their ethnic homelands...Paranoia motivated the Stalin regime to deport these nationalities as a prophylactic measure against diversionist attacks."

In the book The Origins of Soviet Ethnic Cleansing by Terry Martin contains a first person account from 1937 of a deportation. It quotes an Englishman who stood among a group of Russians in Lankaran, Azerbaijan, all watching Turko-Tartars being deported. He received a cryptic explanation from an elderly Russian, that it was "a measure of precaution".

It may be safe to conclude, then, that an average Soviet citizen heard propaganda that the U.S.S.R. was freed of ethnic prejudice, unlike the exploitative imperial powers of the West, but members of an ethnicity of an enemy state were threats to the nation and therefore must be deported as a precaution. And of course, almost all countries except Russia, and ethnicities besides Russian, were threats.