That is a blatant untruth!
When I visited there in 2001, it was about 40% ethnic Russian, 40% ethnic Ukrainian, and 20% Tatar.
But they were practically ALL Ukrainian citizens - and citizenship trumps ethnicity (otherwise, many parts of the U.S. could then be legitimately claimed by, e.g., Mexico or Somalia).
Regards,
I guess you better fix all the news articles and reports then, because everything I've seen says 80%. Wikipedia actually says 82% Russian going by language and 2% Ukrainian, with 20% saying they were Ukrainian by ethnicity.
Ukrainians are just "frontier Russians" anyway, despite the mythology some of them have adopted.