SEOULóNorth Korea appeared to have exploded a nuclear device Tuesday, its third experimental detonation in a long effort to build weapons of mass destruction that the U.S. and other countries consider a serious threat.
An "artificial earthquake" was detected at 11:57 a.m., according to authorities in South Korea who attributed the seismic activity to the northeastern area of North Korea where it previously detonated nuclear devices in October 2006 and May 2009.
North Korea made no immediate statement. Its authoritarian regime gave several explicit warnings since Jan. 24 that it was planning to detonate a nuclear explosive.
Even before those statements, diplomats and observers in other countries had considered such an explosion likely as Pyongyang appeared to be repeating a pattern of provocative actions seen before the previous explosions.
The U.S. Geological Survey said it detected seismic activity with a magnitude of 4.9, bigger than the seismic activity produced in North Korea's previous two blasts. A report by South Korea's Yonhap News Agency said the quake registered a magnitude of 5.1.