The United States has never had fully militarised police before, armed with the kind of high-tech surveillance and weaponry that would never be allowed if the National Guard were called up in an emergency. And neither have we ever had such a malleable definition of what constitutes an emergency. At a time of increasing citizen unrest, it's a volatile combination.
Certainly the government seems to have been preparing for such confrontations for some time now.
Whether the people will accept high-tech "pain compliance" to "modify" dissent remains to be seen. If the attitude towards Tasers is any guide, many won't have a problem with it and "enhanced interrogation" of terrorist suspects has become, at best, a moral grey area for many in the US.
We have essentially normalised torture and created a high-tech police apparatus with more capability than any military in history. Human nature suggests that if you build it, they will use it.