The violence was fomented by conservative agent provocateur James O’Keefe's network, which offered huge sums of money to anarchists if they would disrupt the ceremony and “put a stop to the inauguration,” in effort to portray all the anti-Trump protesters as violent fringe figures.

https://www.youtube.com/watch?v=5WDWLeRKc2Y

There will be provocateurs in the demonstrations to come, just like in the '60s, giving Trump an excuse to act...