The current odds (0.28% as gnabgid@ cites) are still uncomfortable. But also, most of the Earth's surface isn't a city, so maybe we should be even less worried.<p>But on the other hand, I do wonder if a city-killer blast in the wrong spot could trigger some kind of nuclear response in a jumpy geopolitical climate. I keep thinking about the time the USSR caught some weird atmospheric effect and nearly launched, save for the skepticism of a lone individual who chose to break with protocol...