The events in Charlottesville were just one example of the sharp rise in the number of violent confrontations in America between far-right white nationalists and left-wing groups known as 'antifa' - short for "anti-fascists".

Those on the right claim they're fighting to defend free speech or other deeply held American principles. But their opponents say they're promoting extremism and a brand of racial division far out of line with mainstream thought.

Fights that once took place between the two groups online are now spilling out onto the streets of places like Berkeley, California and Portland, Oregon - liberal enclaves where far-right activists have held rallies and which have been turned into scenes of violence, and even murder.

Mike Wendling has travelled to America's west coast to talk to underground antifa organisers and find out what they want - and what they're prepared to do to achieve their aims.

Producer: Anisa Subedar.