Best example is this passage: https://en.wikipedia.org/wiki/Volga_Germans
>The conditions imposed on ethnic Germans by the regime continued to be inhumane.[29][30][31][32] The deportation and subsequent deaths to ethnic minorities during Stalin's rule is referred to as an ethnic cleansing. Some historians refer to these acts as a genocide, though there is debate whether or not the destruction of non-Russians was intentional.[33][34][35][36] Ethnically German minorities received little empathy for mass expulsions due to their German ethnicity and assumed relation to the Nazi regime.[37] There is debate among sociologists and historians whether ethnic cleansing is genocide.[38][39][40]
when USSR does it, it's debatable. there is no clearer example of the friend-enemy distinction.