Ironically, after the Russian Revolution, these same people were harassed and exiled by the new Soviet government in ways very similar to what they had used against the Jews and other ethnic people.
Even more ironically, when these proud Cossacks arrived to America proudly wearing their heavy coats, boots, high hats, and long swords, Americans saw them and were frightened. They urged them to pull off this warmongering costume and to stop their bullying swagger. It wasn't welcomed in the new land where there was a written law in the land and no Czar.