officials to monitor. a truck's just a truck. and this just seems like a very difficult dilemma for counterterrorism officials. >> it's impossible. and this has two purposes. one is that it tells isis supporters to use the tools at their disposal, just what you have at hand. you can't stop people from hijacking trucks. it's just impossible to do that. then psychologically it tells their victims that every truck is a potential terrorist vehicle, a potential weapon that could kill dozens of people. they really do want to sow the fear of every little thing around you including, you know, vehicles, stones, knives that you would get at a kitchen store, all these things can be used and will be. >> part of what i think everyone has a hard time getting their head around is when you see such sociopathic evil of driving a truck into people. how could a person get to a place where they can do that and in some ways that's part of the project about what this book has