| The U.S. Defense Department says it is
still evaluating data from the explosion and small earth tremor in North
Korea on Monday to determine whether it was in fact an underground nuclear
test, as the North Korean government claims.
Nearly two full days after the explosion in North Korea, U.S.
officials, including Pentagon Spokesman Bryan Whitman, cannot say for sure
whether it was a nuclear explosion or not.
He said, "We're continuing to assess the event to determine the veracity of the claim made by the
North Korean government that they conducted an underground nuclear test."
Whitman says it takes time to analyze the seismic data, conduct
atmospheric tests and do other work he cannot discuss to determine what
caused the explosion. And he notes that the work is being done in several
parts of the U.S. government and by government and private researchers
around the world.
Former Defense Department technology official Philip Coyle, who is now
with the Center for Defense Information, says the North Korean event is
particularly hard to analyze.
He said, "Well, a reason it's taking so long is that it appears to be
quite a small nuclear test. Perhaps less than a kiloton, which sounds like
a lot but is actually small as nuclear devices go."
The former official, who has 40 years of experience in nuclear testing
and evaluation, says it is difficult to isolate the impact of such a small
explosion among all the seismic movements detected by sensors in the
region.
But he says once the event is isolated, experts can
determine whether it was an earthquake, a conventional explosion or a
nuclear detonation. He says a nuclear explosion originates from a much
smaller source than an earthquake or conventional explosion of the same
magnitude.
In addition, Philip Coyle says efforts have no doubt been made to
sample the air near North Korea. But he says any exhaust from such a small
test could be very difficult to detect, and North Korea says there was no
such exhaust.
Beyond that, Coyle says, intelligence agencies are also likely seeking
indications of whether the test was real or not.
"There may be some intelligence that intelligence agencies will be able
to get about it, for example, picking up on Internet traffic, voice
messages, things like that. In may be that the National Security Agency
will have some information also," he said.
Another analyst, former CNN reporter Mike Chinoy of the Pacific Council
on International Policy, who has visited North Korea 14 times, says
although it is always difficult to know what the country's leaders are
thinking, he cannot imagine they would pretend to conduct a nuclear test.
He said, "Without being privy to all the scientific and intelligence
information, my own sense is that it would be unlikely for the North
Koreans to risk the kind of reaction they're getting around the world,
politically, or to take the step of announcing it this way, both the
international community and their own people, if they weren't trying to
explode something that had a nuclear component."
Some analysts say the North Korean explosion may have been a failed
nuclear test, or one that worked only partially.
The Washington Times newspaper quotes unnamed U.S. intelligence
officials as saying that is exactly what happened. And a South Korean
newspaper quotes a North Korean diplomat as saying the same thing.
That would fit what is known so far about the North Korean explosion.
Philip Coyle at the Center for Defense Information says there would not
seem to be any reason for North Korea to do such a small test
intentionally, but the secretive state might have wanted to keep the world
guessing.
"If North Korea's purpose here is to be seen as a major nuclear power,
you might think they would want unambiguous test result[s]. But perhaps
they meant to make it small. It's hard to know," he said.
On Tuesday, White House Spokesman Tony Snow said the world may never
know for sure whether the North Korean explosion was nuclear. But the
Pentagon spokesman, Bryan Whitman, said he believes experts will come up
with a clear answer.
He said, "We don't have to guess. We don't have to speculate. We will
know in time. And when we know, I'm sure you'll know."
Whitman would not say how long the analysis will take, but testing
expert Philip Coyle says he thinks there should be a definitive answer
within another couple of days. | 
