In a speech to parliament in Seoul on 13 February, Chung said that, at any rate, North Korea has not tested any atomic weapons. The blasts from tests either below or above ground would have been detected by seismic registers or observation satellites.
Chung was inclined to dismiss the North Korean claim as a bluff, designed to improve Pyongyang's bargaining position at the multilateral talks on its nuclear program.
"There is no doubt that North Korea has 10 to 14 kilograms of plutonium -- with which they could manufacture one or two nuclear weapons," Chung said. "But there is no evidence that the North has turned it into plutonium bombs."
However, adding to the consternation, North Korea announced at the same time that it is pulling out of the six-nation talks, which aim to persuade Pyongyang to drop its nuclear weapons program.
Shannon Kyle, an analyst with the Stockholm International Peace Research Institute, said Pyongyang's assertion it is leaving the six-way talks is not really a surprise, in that the talks have been stalled since last year. He said the real news lies elsewhere.
"What was interesting about the North Korean statement made last week is that not only did they announce they had nuclear weapons, but that they would never give those weapons up," Kyle said. "And that basically undermines the principal U.S. policy goal, which is to get North Korea to agree to the verified and irreversible elimination of its nuclear program. They [in Pyongyang] are now saying flatly that will never happen."
Kyle said assessing exactly what Pyongyang's intentions are is difficult because of what he characterizes as "turmoil" in the North Korean leadership.
"One thing which is important to keep in mind is that there is some sort of internal turmoil taking place within the senior North Korean leadership," he said. "It is not clear exactly what is going on, but we know something is happening there, so that is going to affect the policy-making process because we don't know who actually is deciding [things] at any particular moment."
North Korea's melodramatic style of announcing its moves, plus the widespread belief that an element of bluff is involved, could lead the international community to view the situation as not serious. That would be a mistake, according to Australian Prime Minister John Howard.
"Nobody should imagine that this is anything other than a real problem and one that has to be handled with a great deal of skill and balance," he said.
Certainly, North Korea appears to be ambitious in its development of delivery vehicles for possible nuclear warheads.
It has the No Dong missile with a range of 1,000 kilometers, capable of hitting Japan. As long as seven years ago, it test-fired the Taepo Dong 1 missile with a range of 1,500 kilometers, putting targets in a wide swathe of Russia, Indonesia, and Southeast Asia within range.
Now it is developing the Taepo Dong 2, with a range of up to 6,000 kilometers, making it capable of reaching Central Asia and Alaska. And Pyongyang envisages an even bigger intercontinental rocket with a striking range of up to 12,000 kilometers, which could reach Central Europe and the western United States.
Sounding a warning, UN Secretary-General Kofi Annan says the threat of nuclear proliferation goes far beyond North Korea. Speaking at an international security conference in Munich, Germany, on 13 February, Annan said the world could soon face what he called a "cascade" of countries acquiring nuclear weapons.
He called on the international community to act together to support the Nuclear Nonproliferation Treaty, which he said has held back the floodwaters for decades.
Annan did not mention any country by name. But Kyle said Annan is referring not so much to North Korea as to the neighbors around Iran.
Kyle said he does not see a domino effect developing in Asia, with Japan or South Korea, for instance, developing nuclear weapons in response to Pyongyang. But he says if Iran really is seeking nuclear weapons -- which it denies -- then countries like Syria, Egypt, and Saudi Arabia might be tempted to move down a nuclear path.