N. Korea conducts second nuclear test following rocket launch

(ATTN: UPDATES with warning of more nuclear testing, S. Korean ban on travel to N.
Korea; ADDS background on inter-Korean relations, condolences by N. Korean leader to
Roh Moo-hyun's family, weather agency changing measured tremor)
By Sam Kim

SEOUL, May 25 (Yonhap) -- North Korea said Monday it successfully carried out a
second nuclear test to bolster the "might" of its arms, less than two months
after it launched a rocket that neighbors fear could be turned into a ballistic
missile capable of hitting the U.S.
Its official media said the test was "successful" and "helped satisfactorily
settle the scientific and technological problems" that may have surfaced after it
conducted its first test in October 2006.
South Korea said its weather agency detected tremors of "an artificial
earthquake" measuring at 4.4 on the Richter magnitude scale in the northeastern
part of the communist neighbor at 9:54 a.m. The agency initially said it measured
4.5.
The 2006 test registered a magnitude of 3.6, according to South Korean officials.
The Joint Chiefs of Staff said North Korea coupled the latest underground
detonation with a short-range missile test launched from the same coastal base
that it used to conduct its April 5 rocket launch.
A North Korean diplomat in Moscow threatened his country may step up its nuclear
testing "if the U.S. and its allies continue their policy of intimidation,"
Itar-Tass news agency reported.
The U.S. refrained from confirming the North Korean announcement, but President
Barack Obama called the situation "a threat to international peace."
"The danger posed by North Korea's threatening activities warrants action by the
international community," he said.
Russia said the "nuclear" blast appears to have had a force of up to 20 kilotons,
according to its state media. A nuclear test is considered successful if it
produces a yield of 5-15 kilotons. The U.S. believes the North's 2006 explosion
yielded less than a kiloton.
A kiloton is equivalent to 1,000 tons of TNT.
"The current nuclear test was safely conducted on a new higher level in terms of
its explosive power and technology of its control," the North's Korean Central
News Agency said, monitored in Seoul.
The test, which South Korea said appears to have taken place in Poongkye-ri,
North Hamgpyong Province -- the site of the 2006 blast -- was aimed at "further
increasing the power of nuclear weapons and steadily developing nuclear
technology," the report said.
"The nuclear test is a serious threat to peace and stability on the Korean
Peninsula," South Korean presidential spokesman Lee Dong-kwan said in a
statement, calling it "intolerable" and "a serious challenge to the international
regime on nuclear non-proliferation."
The Unification Ministry in Seoul temporarily barred its nationals from traveling
to the communist neighbor, with the exception of those traveling on business to
the joint industrial complex in the North Korean border city of Kaesong.
In a meeting with his Japanese counterpart Hirofumi Nakasone, South Korean
Foreign Minister Yu Myung-hwan agreed to push for a U.N. Security Council
emergency meeting, while the defense ministry in Seoul placed its 655,000 troops
on a heightened alert.
Chinese Foreign Minister Yang Jiechi, in his talks with Yu, urged that regional
peace and stability be given top priority in dealing with North Korea's action.
Diplomatic sources said Pyongyang gave Beijing prior notice of its nuclear test.
Since the U.N. Security Council condemnation of its rocket launch, North Korea
has threatened additional nuclear and missile testing, vowing to toughen its
"nuclear deterrent against U.S. hostilities."
Pyongyang claims it put a satellite in orbit with the launch while Seoul and
Washington say nothing entered space, calling the move a provocative test of
long-range ballistic missile technology.
South Korean and U.S. experts downplay the ability of the communist regime to tip
its intercontinental ballistic missiles with nuclear bombs.
Protesting the international objection to its rocket launch, North Korea has
vowed to jettison the six-nation denuclearization-for-aid talks and expelled
outside monitors from its nuclear facilities.
The North is believed to have plutonium enough to create up to six nuclear bombs.
It has vowed to restore its Yongbyon nuclear reactor, which had been undergoing
disablement under a pact signed by the two Koreas, the U.S., Japan, Russia and
China.
Yang Moo-jin, a professor at the University of North Korean Studies in Seoul,
said North Korea is stepping up its pressure on Washington so it can squeeze
"maximum" concessions.
Its leader Kim Jong-il also knows that U.N. sanctions, imposed after the 2006
test, would have little economic impact on his already isolated country, Yang
said.
"Kim is following his roadmap under meticulous calculations," he said. "After the
sanctions and temporary condemnations, he is looking at maximizing profits North
Korea may get by holding nuclear disarmament talks with the U.S."
Yang added North Korea appears to be expecting increased internal military unity
as a result of the nuclear test.
South and North Korea remain technically at war after the 1950-53 Korean War
ended in a truce rather than a peace treaty. Their ties deteriorated to their
worst level in a decade after President Lee Myung-bak took office in Seoul early
last year with a pledge to tie reconciliation to North Korean efforts to disarm.
The latest test came hours after Kim Jong-il sent condolences over the death of
former South Korean President Roh Moo-hyun, who leapt from a cliff on Saturday
amid pressure from a corruption scandal involving his confidants and family.
Roh and Kim met in Pyongyang in 2007 for the second-ever summit between the two
countries. The first was held in 2000, leading to a series of reconciliatory
projects, including the Kaesong complex.
South Korea's stock and currency markets briefly tumbled after the North Korean
announcement of a nuclear test, but recovered most of their earlier losses.
The benchmark Korea Composite Stock Price Index (KOSPI) fell 2.85 points, or 0.2
percent to 1,400.90. The local currency closed at 1,249 won to the U.S. dollar,
down 1.6 won from Friday's close.
samkim@yna.co.kr
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