WASHINGTON — U.S. and South Korean officials reported seismic activity in North Korea on Tuesday that appeared to be evidence of the country's third, long-threatened nuclear test and a new challenge for the Obama administration in its effort to keep the country from becoming a full-fledged nuclear power.
''We believe that North Korea has conducted a nuclear test,” said Kim Min-seok, spokesman of the South Korean Defense Ministry.
The shock appeared to be centered in the same location where the North conducted tests in 2006 and 2009, and the U.S. Geological Survey said it was only a kilometer underground, all indications consistent with a nuclear blast. If confirmed, the test would be the first under the country's new leader, Kim Jong Un, and an open act of defiance to the Chinese, who urged the young leader not to risk open confrontation by setting off the weapon. Just in the past few days a Chinese newspaper that is often reflective of the government's thinking said the North must “pay a heavy price” if it proceeded with the test.
But past U.N. Security Council sanctions have not deterred the country from accelerating its missile and nuclear programs. And recent actions, including a successful missile test nearly two months ago that reached as far as the Philippines and sent a washing-machine sized satellite into space have dashed hopes that the country's Swiss-educated new leader might be willing to focus on economic reform rather than pursuing the path taken by his father and grandfather: open defiance of the country's adversaries.
The Obama administration has already threatened to take additional action to penalize the North if it conducts a test, through the United Nations. But the fact is that there are few sanctions left to apply against the most unpredictable country in Asia. The only penalty that would truly hurt the North would be a cutoff of oil and other aid from China. And until now, despite issuing warnings, the Chinese have feared instability and chaos in the North more than its growing nuclear and missile capability, and the Chinese leadership has refused to participate in sanctions.
Kim, believed to be about 29, appears to be betting that even a third test would not change the Chinese calculus.
It may take days or weeks to determine if the test, if that is what it proves to be, was successful. But U.S. officials will also be looking for signs of whether the North, for the first time, conducted a test of a uranium weapon, based on a uranium enrichment capability it has been pursuing for a decade. The past two tests used plutonium, reprocessed from one of the country's now-defunct nuclear reactors. While the country only has enough plutonium for a half-dozen or so bombs, it can produce enriched uranium well into the future.
No country is more interested in the results of the North's nuclear program, or the Western reaction, than Iran, which is pursuing its own uranium enrichment program. The two countries have long cooperated on missile technology, and many intelligence officials believe they share nuclear knowledge as well, though so far there is no hard evidence. The Iranians are also pursuing uranium enrichment, and one senior U.S. official said two weeks ago that “it's very possible that the North Koreans are testing for two countries.” Some believe that the country may have been planning two simultaneous tests, but it could take time to sort out the data.
The timing of the test, if that is what it was, is critical. It comes just as a transition of power is about to take place in South Korea, and the North detested the South's hardline outgoing president, Lee Myung-bak. By conducting a test just before he leaves office, the North could be both sending a message and giving his successor, Park Guen-Hye, the chance to restore relations after the breach a test will undoubtedly cause.
Western officials considered the country's first nuclear test, in 2006, a fizzle, but the next one in 2009 was judged more successful.
While intelligence officials in Washington and Seoul are jittery about the North's progress, there is still no proof that it has yet mastered the difficult technology of miniaturizing bombs so they can be fitted to ballistic missiles. But arms experts declared a recent rocket launching a success, suggesting the country was making advances that could eventually allow it to lob a nuclear-tipped missile as far as the U.S. mainland.
The nuclear test came just weeks after the U.N. Security Council unanimously passed a Washington-led resolution calling for the tightening of sanctions against North Korea for that rocket launching, a violation of earlier resolutions prohibiting the country from testing ballistic missile technology.
Stung by the promise of stiffer sanctions, Pyongyang ratcheted up its threats, vowing to build its capacity to “target” the United States in its most explicit warnings yet. The statement last month, one in a series of threatening missives over several days, said the country planned to test more long-range rockets ("one after another") and to conduct a nuclear test, despite Washington's warning that such actions would lead to more penalties for the impoverished country.
(Pyongyang has often lashed out when it felt ignored, especially by the United States. It was unclear if the untested Kim was following a pattern of behavior perfected by his father, in which the North provoked the West and Seoul to win more badly needed aid as an inducement to draw it back to international negotiations on its weapons programs. North Korea under his leadership may have turned even more recalcitrant, declaring after the United Nations resolution that it would shun any talk of denuclearizing the peninsula, the objective of international talks over two decades.
North Korea, an isolated police state, considers its nuclear and missile programs the linchpins of its survival, both for extracting financial help and for fending off attacks by its enemies. The Kim dynasty, founded by Kim Jong Un's grandfather, has also used the weapons programs to bolster the morale and loyalty of its people, who have been told that were it not for the ruling family's decision to develop nuclear weapons, the United States would invade and make Korea a “colony,” as Japan did in the early 20th century.
Analysts suspect that Kim, in the face of more sanctions, might have felt a more urgent need to assert his standing among his people, who continue to suffer crippling food shortages they are told is the price of developing a costly and credible deterrence. He also might have needed to boost his standing with the hard-line military, which has been considered crucial to keeping the Kims in power, analysts said.