I agree with your statement that regardless of where it comes from, violence is wrong.  It is the press, however, that has identified these individuals as antifas, or leftists.  They create violence wherever they go, and without provocation.  There does not even need to be conflicting opinions present.  In Seattle, and Berkley, for example they are the only ones to be present and they cause injury and destruction.  They feed off of rhetoric of the likes spewed out by Schwab.