Indications that the test had taken place first emerged when U.S. seismologists reported a disturbance Tuesday morning in North Korea centered near the site of the secretive regime's two previous atomic blasts. The area around the epicenter of the tremor in northeastern North Korea has little or no history of earthquakes or natural seismic hazards, according to U.S. Geological Survey maps.
The disturbance reported Tuesday had a magnitude of 5.1 -- upgraded from an initial estimate of 4.9 -- and took place at a depth of about one kilometer, the USGS said. Kim Min-seok, a spokesman for the
South Korean Defense Ministry, said the magnitude of the "artificial tremor" suggested the size of the blast could be in the order of 6 to 7 kilotons, more powerful than the North's two prior nuclear tests.
That calculation, though, was based on the USGS's initial estimate of a 4.9-magnitude seismic disturbance, he said. A 5.1-magnitude tremor could indicate a 10-kiloton explosion.
The test was designed "to defend the country's security and sovereignty in the face of the ferocious hostile act of the U.S.," the North's state-run Korean Central News Agency said, referring to new U.S.-led sanctions on Pyongyang after the recent launch of a long-range rocket.
North Korea's nuclear test prompted united condemnation and a vow of tough action from the
U.N. Security Council on Tuesday. The council issued a statement slamming the underground nuclear test that jolted the already fragile security situation in Northeast Asia. South Korean Foreign Minister
Kim Sung-hwan, repeating a statement to reporters outside council chambers, said the test violated council resolutions, and "there continues to exist a clear threat to international peace and security." Kim said council members will start work "on appropriate measures in a Security Council resolution" and that
"North Korea will be held responsible for any consequences of this provocative act." The council is chaired this month by South Korea. The Security Council last month promised "significant action" if another North Korean nuclear test occurred. The test probably took place near P'unggye and yielded
"several kilotons," according to assessments cited by the U.S. director of national intelligence. It drew condemnation from around the globe and prompted the emergency Security Council session Tuesday morning. It is the first nuclear test carried out under the North's young leader, Kim Jong Un, who appears to be sticking closely to his father's policy of building up the isolated state's military deterrent to keep its foes at bay, shrugging off the resulting international condemnation and sanctions. State
Department spokeswoman Victoria Nuland said North Korea told the department "through our usual channel" of its "intention to conduct a nuclear test without citing any specific timing prior to the event."
After Kim Sung-hwan spoke, Susan Rice, the U.S. ambassador to the United Nations, told reporters outside the council chambers that the panel met to discuss what she called a "provocative test" and an action that council members regard as "regrettable." The test violates North Korea's obligations under several unanimous council resolutions, she said.
According to http://www.nytimes.com/2013/02/12/opinion/north-koreas-lesson-nukes-forsale.html?_r=0 North Korea’s message is that nukes are for sale.