Washington (CBS/AP) - North Korea boasted Monday that it successfully tested a nuclear weapon, sparking a barrage of global condemnation over an underground blast that appeared to thrust the volatile communist state into the elite club of nuclear-armed nations.
President Bush said Monday that the reported North Korean nuclear test poses a threat to global peace and security and denounced it as "unacceptable."
Speaking at the White House Monday morning, Mr. Bush said the U.S. “condemns this provocative act,” but said he was not yet able to confirm whether the test had in fact been nuclear.
Mr. Bush said North Korea was a “leading proliferator of missile technology,” and accused Pyongyang of transferring such technology to Iran and Syria.
The president said that North Korea exporting nuclear materials or technology to either of these nations, “would be considered a grave threat to the United States,” and that the regime would be held “fully accountable for the consequences of such actions.”
Mr. Bush said the U.S. remained “committed to diplomacy,” and urged the United Nations Security Council to act quickly against the North.
The explosion prompted worldwide concerns that it could seriously destabilize the region, and even Pyongyang's ally China said it strongly opposed the move.
Officials in South Korea and France said the blast was relatively small, while Russia said it had been perhaps as powerful as the nuclear bombs the U.S. dropped on Japan during World War II.
Nuclear Arms Expert Peter Zimmerman told CBS News' The Early Show that, judging from the seismic disruptions measured at the time of the alleged test, the blast was fairly small, equivalent of “up to a kiloton and a half” of TNT, no where near the size of blast which leveled Hiroshima.
The atomic bomb that struck Hiroshima, Japan, on Aug. 6, 1945, had the destructive power of about 15 kilotons of TNT.
Russia's Defense Minister Sergei Ivanov said that the force of the blast was between five and 15 kilotons and that there was “no doubt” there had been a nuclear blast, the RIA-Novosti news agency reported.
South Korea's seismic monitoring center said a magnitude 3.6 tremor felt at the time of the alleged nuclear test wasn't a natural occurrence.
The U.S. Geological Survey said it recorded a seismic event with a preliminary magnitude of 4.2 in northeastern North Korea coinciding with the test claim, but survey official Bruce Presgrave said the agency was unable to tell if it was an atomic explosion or a natural earthquake.
The North's official Korean Central News Agency said the underground test was performed successfully “with indigenous wisdom and technology 100 percent,” and that no radiation leaked from the test site.
“It marks a historic event as it greatly encouraged and pleased the (Korean People's Army) and people that have wished to have powerful self-reliant defense capability,” KCNA said, adding that it was “a great leap forward in the building of a great prosperous powerful socialist nation.”
If details of the test are confirmed, North Korea would be the ninth country known to have nuclear weapons, along with the United States, Russia, France, China, Britain, India, Pakistan and Israel.
The United Nations Security Council was to discuss the test at a meeting Monday morning at the organization's headquarters in New York, according to a U.S. official.
The meeting was previously scheduled to hold a vote for Secretary General Kofi Annan's successor, likely to be South Korean Foreign Minister Ban Ki-moon. Ban has said his first act as Secretary General would be to travel to Pyongyang to discuss the nuclear standoff.
British Ambassador to the U.N., Emyr Jones-Parry, said on his way into the meeting that he did not have any further information regarding the nature of the test, and that the Council's decision on how to react would depend on that information becoming available.
A Security Council resolution adopted in July after a series of North Korean missile launches imposed limited sanctions on North Korea and demanded the country rejoin international nuclear talks. The North immediately rejected the plea.
A nuclear North Korea would dramatically alter the strategic balance of power in the Pacific region and seriously undermine global anti-proliferation efforts. Japanese Prime Minister Shinzo Abe said the test would mark the beginning of a “dangerous nuclear age” in north Asia.
CBS News correspondent Barry Petersen said Japan would likely join the U.S. in seeking additional sanctions against Pyonyang, and would probably also look to implement a space-based missile detection and destruction system in partnership with Washington.
Zimmerman said Abe would be looking for the U.S. to reaffirm its guarantee to protect Japan in the face of aggression, a commitment the White House renewed on Monday.
CBS News national security correspondent David Martin said the U.S. government’s response may include a naval blockade of North Korea. Martin said the North doesn’t have the capability to launch a nuclear-tipped missile yet, making the primary concern the possibility that Pyongyang might export nuclear material or technology to nations such as Iran or Syria, or to a terrorist group.
Britain's Prime Minister Tony Blair said the test was a “completely irresponsible act,” and its Foreign Ministry warned of international repercussions.
Japan's Abe, in Seoul for a summit meeting, said the “the development and possession of nuclear weapons by North Korea will in a major way transform the security environment in North Asia and we will be entering a new, dangerous nuclear age.”
He said Japan would consider “harsh measures.”
“North Korea will be held responsible for the situation it has created,” Abe said.
On Sunday in Beijing, Abe and Chinese President Hu Jintao had pledged to work together to avert a North Korean test.
China, the North's closest ally, said on Monday that Beijing “resolutely opposes” the North Korean nuclear test and hopes Pyongyang will return to disarmament talks.
CBS News senior White House correspondent Bill Plante said there was no military planning underway in Washington for any type of offensive against North Korea, and that President Bush’s government was still relying on a the framework of the stalled six-party talks to resolve the nuclear issue.
In Tokyo, Petersen said the “use of force is not an option here” due to fears of the North retaliating — it has at its command a standing army of more than 1 million and a host of conventional weaponry — against its neighbors.
Plante said U.S. officials may be hoping the North’s actions will serve to “wake up” South Korea to the threat posed by its northern neighbor. Plante said many in the U.S. think South Korea has been too soft on Kim Jong Il’s regime.
South Korean President Roh Moo-hyun said the test would make it difficult for Seoul to maintain its engagement policy with its communist neighbor.
“This is a warning as well as my prediction,” Roh told journalists after his summit with Abe. “Under this situation, it's difficult for South Korea to maintain engagement policy.”
“South Korea won't be patient for everything, make concessions on everything and accept all demands from North Korea as it did in the past,” Roh said.
The North is believed to have enough radioactive material for about a half-dozen bombs. It insists its nuclear program is necessary to deter a U.S. invasion.
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