Is Kim Jong-il building a new type of weapon? On Monday Seoul announced that the Korea Institute of Nuclear Safety had detected unusually high levels of xenon gas near the North Korea border on May 14. The concentration of xenon was eight times higher than normal, and the presence of the gas is indicative of nuclear activities. Because the wind was blowing south at the time, the source of the gas could not have been one of South Korea's nuclear plants. The xenon might have originated in China or Russia, but the most likely place was the land of unexplained...