WASHINGTON—The United States reported Monday that radiation-detecting aircraft had confirmed that North Korea conducted an underground nuclear test a week ago.
Director of National Intelligence John Negroponte's office said in a statement that airborne sensors last Wednesday detected "radioactive debris," confirming that a nuclear test took place near P'unggye, in northeastern North Korea. "The explosion yield was less than a kiloton," it added.
Since North Korea announced its first nuclear detonation on Oct. 9, aircraft with sophisticated radiation monitoring equipment operated by the Florida-based Air Force Technical Application Center have been trolling the skies for conclusive evidence.
There has been speculation that the North Korean test, which prompted worldwide alarm, was a partial failure. Pyongyang reportedly told China beforehand that the blast would have an explosive yield of 4 kilotons, but seismographs detected a much smaller blast. The statement didn't speculate on why the explosion was less powerful than expected.
A kiloton is the equivalent to the explosive force of 1,000 metric tons of TNT.
Confirmation of the nuclear test came as Secretary of State Condoleezza Rice prepared to travel to East Asia to confer with China and other regional powers on implementation of new U.N. sanctions on North Korea.
A U.N. Security Council resolution approved Saturday calls on nations to inspect cargo going to and from North Korea to stop material that could aid its work on nuclear weapons or other advanced armaments, such as ballistic missiles.
China, which shares a border with North Korea, has shown little enthusiasm for the measure, apparently fearing it could lead to military confrontation.
"We expect every member of the international community to fully implement all aspects of this resolution, and we expect the Security Council to aggressively monitor the process," Rice said at a briefing. She plans stops in Japan, South Korea, China and Russia.
"I am not concerned that the Chinese are going to turn their backs on their obligations," she said. "I don't think they would have voted for a resolution that they did not intend to carry through on."
Earlier, Undersecretary of State Nicholas Burns, in an interview with National Public Radio, cited news reports that China had begun to inspect truck cargo along its 880-mile border with North Korea.
But Beijing's ambassador to the United Nations, Wang Guangya, made a distinction between inspecting cargo and stopping it.
"Inspections, yes. But inspection is different from interception and interdiction," Wang said. "In that area, I think that different countries will do it in different ways."
Rice said she would also talk with U.S. partners in East Asia about designing systems to combat trafficking in materials used to make weapons of mass destruction.
President Bush said last week that the United States would hold North Korea "fully accountable" if it transferred nuclear weapons or material to a third party.
However, China and South Korea so far have declined to join the U.S.-led Proliferation Security Initiative, which is designed to stop such trade.
Rice rejected criticism that the troubled U.S. occupation in Iraq has weakened Washington's ability to deal with nuclear threats from North Korea and Iran, which ignored a U.N. deadline to halt uranium enrichment.
"The Iranian government is watching and it can now see that the international community will respond to threats from nuclear proliferation," she said.
(c) 2006, McClatchy-Tribune Information Services.
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