Piano2,
I am a firm believer in everyone's right to the Freedom of Speech but not violence.
None of hate groups are new. They just haven't been vocal for awhile. 
I remember when they use to march in parades in uniform to flaunt their freedom in our faces. 
The best defense against hate groups, and I include the Anarchists and the newer groups, is to be aware of them!  
Then denounce them and peacefully protest against them. 
Back twenty plus years ago, our community in Lower Southeast Alaska, every post office box holder and address received,the most vile,hate filled,racist, bigoted mailing. It was full of hate for people of every color but white, religions (Catholic, Latter Day Saints, Seventh Day Adventist, Jehovah Witnesses) it also targeted the President and former presidents and the SCOUS. The return address was a church in Missouri but was mailed from a neighboring island. I was proud of our community's outrage and how people returned the mailing as "refused" which cost them $$.