Depends on what you mean by "big." If by that you mean "a few hundred of them spread over the millions of square miles of the American West, then yes, they're big. But I have never heard of them kidnapping a fa,o;u off a public highway and murdering them because one of them was of a different race. Was that what you had in mind?
If you're from Moldova you may not realize that things are not as wild in America as is sometimes said in the rest of the world.
As a practical matter, an oriental/caucasian couple is going to be pretty far down on the list of concerns for most racists.