The continuing crisis in Japan from the near-meltdown of the Fukushima reactor is terrifying in its own right. But it also raises the question of another, even deadlier nuclear threat.
The evacuations now going on in Japan would pale in comparison to what would be necessary if just one 100-kiloton nuclear bomb were to go off near a major city - not to mention the immediate deaths caused by the bomb, which could reach into the hundreds of thousands. And a 100-kiloton bomb is among the smallest in the U.S. or Russian arsenals.