There is still very little risk of nuclear terrorism in the US, particularly as all of the large terrorists groups seeking to attack the US have been suppressed, at least for now. Yes, it would only take one crazy person to hit the US, but one crazy person doesn't generally have access to nuclear weapons.
Moreover, global warming is a much bigger risk right now. A nuclear terrorist event would take out a city. Global warming has the potential to take out every city on our coast, not to mention many of our allies' cities.
I know it makes a great soundbite for your nuclear conference, but I also hope that you actually know better.