Anxiety grows over North Korea's arsenal: 'Danger now is miscalculation'

On the day of North Korea's first atomic test in 2006, aides to President George W. Bush began phoning foreign capitals to reassure allies startled by Pyongyang's surprising feat. The test, aides said, had been mostly a failure: a botched, 1-kiloton cry for attention from a regime that had no warheads...