North Korea has drawn universal condemnation following its announcement yesterday that it had carried out an underground nuclear weapons test. It also apparently test-fired several short-range missiles.

Russian officials said the nuclear weapon was comparable to those that destroyed Hiroshima and Nagasaki.

Russia’s Foreign Ministry called it ‘a serious blow to international efforts’ to prevent the spread of nuclear weapons.

North Korea tested its first nuclear weapon in October 2006 in defiance of international opinion. That led the United Nations to pass a resolution condemning the test and imposing sanctions on the country.

The new test comes less than two months after North Korea drew wide condemnation by test-firing a long-range ballistic missile on April 5. It had threatened the latest action unless the United Nations Security Council apologized for condemning that missile test and tightening sanctions.

After the Security Council refused to apologize, North Korea expelled international inspectors, threatened to restart its Yongbyon nuclear reactor — which it had agreed to start dismantling in 2007 — and left the six-party talks aimed at resolving the nuclear issue.

North Korea’s official KNCA news agency said on Monday, ‘We have successfully conducted another nuclear test on 25 May as part of the republic’s measures to strengthen its nuclear deterrent.’

The 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.”

Russian military experts estimated the explosion’s yield at between 10 and 20 kilotons, many times more than the 1 kiloton measured in North Korea’s first nuclear test in 2006. One kiloton is equal to the force produced by 1,000 tons of TNT.

The force of the blast made the ground tremble in the Chinese border city of Yanji, 130 miles away, news reports said.

The North Korean news agency said, “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.’

However every one of North Korea’s neighbors, including its closest ally China, strongly condemned the test.

China’s Ministry of Foreign Affairs issued a statement saying it was ‘resolutely opposed’ to the nuclear test, and that North Korea had “disregarded the opposition of the international community.’ China urged North Korea to avoid actions that would sharpen tensions and to return to the six-party disarmament talks.

South Korea and Japan both assailed the nuclear test. Japan said it would seek a new UN resolution condemning the test.

United Nations Secretary General Ban Ki-moon said he was ‘deeply worried’ by the development. The Security Council will hold an emergency meeting in New York this afternoon to discuss the situation.

The Obama administration, less than three weeks ago, announced a new diplomatic effort to restart the stalled talks with North Korea about its nuclear program. On Monday, the White House said the nuclear test was in ‘blatant defiance’ of the United Nations.

North Korea’s action is seen by some commentators as a direct challenge to Obama’s efforts to stop the spread of nuclear weapons.

Kim Myong-chol, executive director of the Centre for Korean-American Peace in Tokyo, who is close to Pyongyang, said the test was a reminder that North Korea ‘is going it alone as a nuclear power,” the UK Guardian reported.

‘North Korea doesn’t need any talks with America. America is tricky and undesirable,’ he said. ‘It does not implement its own agreements.

‘We are not going to worry about sanctions. If they sanction us, we will become more powerful. Sanctions never help America; they are counter-productive … We don’t care about America and what they say.’

However Paik Hak-soon of the South Korean security think tank Sejong Institute told The Associated Press that he believes North Korea is ‘putting maximum pressure’ on the United States for direct, high-level negotiations resulting in a ‘grand deal’ that would include aid, concessions and a normalization of ties.

North Korea is also holding two American journalists, Laura Ling and Euna Lee — accused of entering the country illegally and engaging in ‘hostile acts’ — who are set to stand trial in Pyongyang on June 4.

Their case may serve as a face-saving way for the U.S. to send a high-level envoy to Pyongyang for negotiations, Paik said.

‘Had it not been for the journalists, it could give an impression of yielding to North Korea’s provocation if the U.S. sends a high-level envoy for direct talks with Pyongyang,’ he said.

Some analysts believe that North Korean leader Kim Jong-il wants to use the test to shore up domestic support amid speculation that he is about to name one of his three sons as his successor.