Via AP:
North Korea's neighbors are looking for radiation from its nuclear test, but they might not find any.
The North said the underground test site where it detonated what it described as a hydrogen bomb did not leak radioactive materials. If that's true, it will be difficult for outsiders to determine whether the device was indeed a thermonuclear weapon or a simpler nuclear bomb.
Japan's Nuclear Regulation Authority says no abnormal change in radiation levels had been detected on monitoring posts across the country as of Sunday night.
China's National Nuclear Safety Administration says it activated nuclear radiation-related environmental contingency plans shortly after the test was conducted. It said in a statement on its website that automatic environmental radiation monitoring stations in China's northeast were operating normally.