Too early to conclude if NKorea blast was nuclear: experts
Any conclusions on the nuclear nature of Monday's underground blast in North Korea would be premature at present, the Comprehensive Test Ban Treaty Organization said on Friday.
"Finding nothing today means nothing," said Lassina Zerbo, director of the International Data Center at the CTBTO, a monitoring body.
None of the organisation's stations has yet detected any nuclear material, and earlier Friday a US military official said an initial analysis of air samples collected by an aircraft showed "no evidence of nuclear debris".
But the fact that the test was carried out underground means that nuclear particles may only emerge at a later stage, a European diplomat said at a special session of the CTBTO Preparatory Commission here.
Also, winds may not have been in the right direction for the stations to pick up any suspect particles, Zerbo said.
The CTBTO has stations just outside North Korea, notably in China and Japan.
"They have filters which suck in ambient air, but they have to be pointed in the right direction for the wind. And a certain amount of time has to be allowed before the particles reach the station," Zerbo said.
Earlier, the White House was also circumspect in its conclusions, saying it had no definitive word on whether North Korea had carried out the nuclear test as intelligence agencies were still conducting an analysis.
"We still do not have any definitive statement on it. We talked to DNI (the Director of National Intelligence's office) just a couple of minutes ago. They still think the analysis that they are doing may take take another day or two," White House spokesman Tony Snow said.
Seismographs detected a blast in North Korea estimated at the equivalent of 200 tons of TNT, unusually low for a first-time nuclear explosion. Historically, these have ranged between four and 12 kilotons.
North Korea is reported to have tipped off China that it was testing a four-kiloton nuclear weapon. It has said the test was conducted underground under very safe conditions.
US intelligence officials say a possible explanation for the low yield is that the North Korea blast might have resulted from a nuclear test that did not go as planned.
But officials also have left open the possibility that a test deep underground may have muffled the seismic shock, leading to a distorted reading of the blast.
For that reason, air samples were considered a key piece of evidence to corroborate the North Korean claim of a successful nuclear test.
US expert John Pike said that North Korea chose to conduct the test underground in order to avoid air contamination and so as not to "provide its enemies with technical information."
North Korea, along with India and Pakistan, is not a signatory to the Comprehensive Nuclear Test Ban Treaty, which has been ratified by 135 states.
At Friday's meeting, a "large number of Signatories States expressed their deep concern and regret over the announcement of the Democratic People's Republic of Korea to have conducted an underground nuclear test on 9 October 2006," a CTBTO statement said.
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