Ever watched "Fiddler on the Roof," Grand Vol? haha!
Yeah, it's historically a problem. Western Russia (which included Ukraine and Poland at the time) were home to numerous Jewish pogroms. Jews were excluded from Slavic society and cossacks occasionally came in to smack some of them around.
Obviously those sentiments remain today, and there is worry that the neo-fascists, ultranationalist elements of the pro-Ukrainian group will resort to human rights violations. Honestly, though, Russia just says this. They couldn't give a crap about Jews either.