The US has been asleep at the wheel with domestic extremist groups... even Timothy McVeigh (who was part of a huge chain of hatemonger "patriots" who egg each other on) they tried to pawn off as a lone wolf. Its a weird loosely connected mob of neo-christo-white-nazi-fruitloops dotting the US. The intertubes give them synergy...
and the Tea Party rank and file is the "civil" facade of much of it, funded by libertarian mil/billionaires.