TOKYO, Jan. 7 (UPI) -- The probability is low North Korea tested a hydrogen bomb, a Japanese official said, a day after the White House expressed skepticism over Pyongyang's claims it had successfully tested an enhanced nuclear fission device.
Tokyo's Defense Minister Gen Nakatani told reporters that it would be "difficult to reason North Korea tested a typical hydrogen bomb," Jiji Press reported.
Nakatani said the scale of the seismic waves of the quake detected along the North Korea-China border was too weak to conclude a hydrogen bomb was tested.
South Korean news outlet News 1 reported seismic monitors detected a 4.6 tremor near the Punggye-ri test site, falling short of a 6-7 quake that would result in the wake of a hydrogen bomb detonation.
South Korea and Japan are cooperating closely on North Korea provocations, following Pyongyang's announcement.
China, North Korea's closest economic partner, has not concealed its annoyance with Pyongyang's unexpected foray into what is its fourth nuclear test since 2006. Chinese public opinion, too, is growing increasingly negative toward what many regard as an estranged neighbor.
Ning Ye, a U.S.-based attorney specializing in China affairs, told Boxun News Network nuclear leakages from North Korea tests pose a serious risk to China's northeastern provinces, and that if an accident occurs, a catastrophic nuclear disaster several times more damaging than Chernobyl could impact populations in northeast China and even Beijing.
North Korea's provocations are to be a topic of discussion during a call scheduled for Friday between South Korean Foreign Minister Yun Byung-se and his China counterpart Wang Yi, Yonhap reported.
Seoul is expected to request Beijing to push for tougher measures against Pyongyang at the United Nations Security Council.