Feds already know. White groups make it known who they are and what they represent. We even know the ones here in Hawaii. Military also knows who they are and there are lots of them at Schofield. Black ones too. Same way Feds track international terrorist, they track domestic terrorists. Just can't use intelligence in a court of law. Domestic groups can hide behind First Amendment and have access to very good attorneys who are First Amendment and Second Amendment experts. Randy Weaver is considered a hero in country American. So is Bo Grits,  ended Ruby Ridge seige.