Ahn Young-Joon/Associated Press
WASHINGTON — North Korea confirmed on Tuesday that it had conducted its third, long-threatened nuclear test, according to the official KCNA news service, posing a new challenge for the Obama administration in its effort to keep the country from becoming a full-fledged nuclear power.
The KCNA said it used a “miniaturized and lighter nuclear device with greater explosive force than previously” and that the test “did not pose any negative impact on the surrounding ecological environment.”
The test led to a crescendo of international condemnation Tuesday, with President Obama calling it a “highly provocative act” that demands “swift and credible action by the international community” against North Korea. Russia, Britain, South Korea and the United Nations similarly swiftly condemned the blast. The United Nations Security Council scheduled an emergency meeting at 9 a.m. New York time to take up the matter.
Preliminary estimates by South Korea suggested the test was much more powerful than the previous two conducted by the North.
Kim Min-seok, a spokesman for South Korea’s Defense Ministry, said Tuesday’s blast generated an explosive yield of between six and seven kilotons, far greater than the yield of less than one kiloton detected in the North’s 2006 test and an estimated yield of two to six kilotons in its 2009 test. But it appeared less powerful than the first bomb the United States dropped on Japan, in Hiroshima in 1945, which had an explosive yield of 15 kilotons.
The test is 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. In a statement issued several hours after the blast, China expressed its “staunch opposition” to the test but called for “all parties concerned to respond calmly.” And it was unclear how China would act at the United Nations Security Council as it convenes Tuesday.
The nuclear test came the same day President Obama is to use his State of the Union address to call for drastically reducing nuclear arms around the world, potentially bringing the number of deployed American weapons to roughly 1,000 from the current 1,700.
Even before Pyongyang conducted Tuesday’s test, the Obama administration had already threatened to take additional action to penalize the North 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.
Mr. Kim, believed to be about 29, appears to be betting that even a third test would not change the Chinese calculus.
The test set off a scramble among Washington’s Asian allies to assess what the North Koreans had done.
The United States sent aloft aircraft equipped with delicate sensors that may, depending on the winds, be able to determine whether it was a plutonium or uranium weapon. The Japanese defense minister, Itsunori Onodera, said Japan had ordered the dispatch of an Air Self-Defense Force jet to monitor for radioactivity in Japanese airspace.
Japan’s new prime minister, Shinzo Abe, told Parliament that the country was considering “its own actions, including sanctions, to resolve this and other issues.”
But the threat may be largely empty, because trade is limited and the United States and its allies have refrained from a naval blockade of North Korea or other steps that could revive open conflict, which has been avoided on the Korean Peninsula since an armistice was declared 60 years ago.
It may take days or weeks to determine independently if the test, was successful. American 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 has only enough plutonium for a half-dozen or so bombs, it can produce enriched uranium well into the future.