Neo-Nazism, and race hatred are alive and kicking in the United States. The violence in Charlottesville was shocking not just because a life was taken, but also because of the polarising impact of President Trumps response. Stephen Sackur speaks to Richard Cohen, President of the Southern Poverty Law Centre, a group devoted to civil rights activism. How fanciful is the notion of a 21st century American civil war?(Photo: Richard Cohen on Hardtalk)