Much like the opponents who reacted with violence to the violent SA in Germany in the 20s and 30s, antifa started to arm themselves when they felt "outgunned" by Trump supporters at a Berkeley event. Before then they pretty much limited their activity to shouting their opponents down and property damage. But now that the neo-nazis and white supremacists were accompanied by militia groups armed with automatic rifles and in Charlottesville, and one of them used a weaponized car, I'm afraid that antifa will escalate too. This arms race will not end well.