> Can you imagine if Russians were a another "race".
> Alas, they cannot make such accusations.
Why not? Can you prove that Russians are "another race"?
Is there such thing as a scientific definition that states unambiguously where any one race ends and another begins? I don't doubt that populations of humans commonly share family lineage, phenotypes, and genotypes, but the concept of "race" escapes any sufficient definition or real world testability.
US state laws and culture had for a long time considered the "one-drop"[1] (of blood of a different race) a disqualifier for being considered a White American. The implication is that if you can't prove your pedigree back infinitely far, you are more likely that not to not be white.
In fact, using some inductive logic, it's almost perfectly likely that every person is "mixed-race" if you search back far enough.
This is all to say that "racism" is a description of how people see (and treat) other people. It's rarely been about actual pedigrees and almost entirely been about mental classification of others.
[1] https://en.wikipedia.org/wiki/One-drop_rule