This video from MSNBC indicates the anarchists are getting violent at anti-Trump protests.

I understand the frustration, but this is harmful to the movement, because if it continues then the peaceful non-violent protesters are going to start staying home.  And then, very very quickly, these huge mass protests we've been seeing are going to be reduced to small handful of people.
If you want to be destructive, then fine, go ahead and be destructive.  But keep that sort of thing as far away from the peaceful protest as possible.   Don't hijack a peaceful protest.  Let people have the option of protesting peacefully if they want to.

As I wrote in 2006:

Ultimately I am not against a “diversity of tactics” per se, but the non-violent form of protest needs to be respected. A demonstration cannot be both violent and non-violent at the same time. I have personally seen in Windsor, Quebec, Washington DC, and Philadelphia violent activists using non-violent activists as a shield. In Quebec for example I was participating in a non-violent sit in, when black bloc activists threw Molotov cocktails at the police from behind the rows of sitting peaceful demonstrators, and then ran away, leaving the non-violent activists to deal with the resulting police tear gas and pepper spray (which the media then blamed the activists for).
If one is truly talking about a diversity of tactics, than non-violent tactics need to be preserved as well. Those wishing to participate in other forms of protest should stay far away from activists engaged in non-violent civil disobedience. They should choose a different date or a different location for violent activities. If they cannot do this, talk of “a diversity of tactics” is hollow. It is also undemocratic.