Opinion: I work to fight terrorism. This is the threat that keeps me up at night

I have traveled the world trying to stop people from radicalizing, and through those experiences I have seen the best and the worst of humanity. I've interviewed numerous terrorists in prison cells, bound by shackles - and sat down to hear the experiences of countless former extremists of all kinds. Most recently, I spoke with a man who was actually convicted of participating in and supporting al-Qaeda plots in Afghanistan and the US.