No need to speculate about motives and objectives.  White nationalists (KKK, Neo-Nazis, Skinheads, etc.) have stated their objectives clearly.  They want a nation in which whites hold all power and wealth, and all others live (or die) under white control.  The leaders (citing the free speech provision) have stated for decades that they would train and increase their numbers, to be ready when the opportunity for takeover came.  Up to now we've had presidents who put them in their place.  They now believe they have a champion in the WH.   It would be naive to believe the Klan, etc. would not have done everything possible including intimidation, to ensure Trump won.  The fact that David Duke endorsed Trump (and he didn't object) should have given us notice of his sympathies.