SEOUL, SOUTH KOREA >> South Korean and international monitoring agencies reported Friday an earthquake near North Korea's northeastern nuclear test site, a strong indication that Pyongyang had detonated its fifth atomic test explosion.
South Korea's Joint Chiefs of Staff said in a statement that "artificial seismic waves" measuring 5.0 were detected near the Punggye-ri test site, and officials were analyzing whether it was a nuclear test.
European and U.S. monitoring services also detected similar seismic activity, with the U.S. Geological Survey calling it an "explosion" on its website.
North Korea conducted its fourth nuclear test earlier this year, part of its push for a nuclear-armed missile that could one day reach the U.S. mainland.
A second nuclear test this year would be a defiant response to Western pressure on Pyongyang to halt its nuclear ambitions. The country has previously conducted tests every three to four years.
Any test will lead to a strong push for new, tougher sanctions at the United Nations and further worsen already abysmal relations between Pyongyang and its neighbors. North Korean nuclear tests worry outside governments because they are seen as moving North Korea's scientists and engineers that much closer to their goal of an arsenal of nuclear-tipped missiles that can reach the United States.