North Korea Conducts Nuclear Test

North Korea today risked further international isolation after it claimed to have successfully tested a nuclear weapon, months after it enraged the US and its allies by test firing a long-range ballistic missile.

The KNCA news agency, the regime's official mouthpiece, said: "We have successfully conducted another nuclear test on May 25 as part of the republic's measures to strengthen its nuclear deterrent."

Officials in South Korea said they had detected a minor tremor consistent with those caused by an underground nuclear explosion. The country's Yonhap news agency quoted a government source as saying that the North had test fired a short-range missile immediately after the nuclear test.

The UN security council will reportedly hold an emergency meeting in New York later today to discuss its response to the latest escalation in the North Korean nuclear crisis.

The North Korean news agency said the test had been "safely conducted on a new higher level in terms of its explosive power and technology of its control.

"The test will contribute to defending the sovereignty of the country and the nation and socialism and ensuring peace and security on the Korean Peninsula and the region."

South Korea and Japan condemned the test, North Korea's second since it exploded its first nuclear device in October 2006 in defiance of international opinion. That test prompted the UN security to pass a resolution banning Pyongyang from activities related to a ballistic missile program.

The South Korean president, Lee Myung-bak, convened a session of the country's security council after seismologists reported earthquakes in the Kilju region, site of the North's first nuclear test.

In Tokyo, Japan's chief cabinet secretary, Takeo Kawamura, said the test was "a clear violation of the UN security council resolution and is absolutely impermissible."

Tibor Toth, a senior official at the comprehensive nuclear test-ban treaty [CTBT] organisation in Vienna, said it "constitutes a threat to international peace and security and to the nuclear non-proliferation and disarmament regime.

"I am gravely concerned by this action. In particular, it is a serious violation of the norm established by the CTBT and as such deserves universal condemnation."

While officials in Washington stopped short of confirming that a controlled nuclear explosion had caused the seismic activity, the US geological survey said a magnitude-4.7 earthquake had been registered in northeastern North Korea at 9:54 am local time.

North Korea had warned of a second nuclear test after the UN condemned its test-launch of a ballistic missile on April 5 and agreed to tighten sanctions put in place in 2006.

Pyongyang insisted it had put a peaceful communications satellite in orbit, but experts said the technology and methods were identical to those used to launch a long-range Taepodong-2 missile.

After the UN refused to apologize for condemning the launch, North Korea expelled international inspectors, threatened to restart its Yongbyon nuclear reactor - which had been partially dismantled - and walked away from six-party nuclear talks.

Today's test will add to fears that the North is moving closer to possessing the ability to mount a nuclear warhead on long-range missiles that are capable, in theory, of reaching Hawaii and Alaska.

"This test, if confirmed, could indicate North Korea's decision to work at securing actual nuclear capabilities," Koh Yu-hwan, a professor at Dongkuk University in South Korea, told Reuters.

"North Korea had been expecting the new US administration to mark a shift from the previous administration's stance, but is realizing that there are no changes. It may have decided that a second test was necessary. [It] seems to be reacting to the US and South Korean administrations' policies."

Analysts believe the North Korean leader, Kim Jong-il, hoped to use the test to shore up support from the military amid mounting speculation that he is about to name one of his of his three sons as his successor.

Kim, 67, appears to be re-establishing his grip on power since reportedly suffering a stroke last August.

Today's test is a direct challenge to attempts by the US president, Barack Obama, to engage the North and stem the spread of nuclear weapons.

Despite promising a fresh start to bilateral relations, Obama, who denounced last month's missile launch as "a provocation," has so far failed to persuade the North Koreans to enter into negotiations.

In a statement carried by KCNA, the North Korean foreign ministry said: "The study of the policy pursued by the Obama administration for the past 100 days since its emergence made it clear that the US hostile policy toward [North Korea] remains unchanged.

"There is nothing to be gained by sitting down together with a party that continues to view us with hostility."