Did Kim Jong Il secretly travel to Beijing to confer about a possible test of North Korea's nuclear weapons – or is he about ready to do so?

The Guardian writes that South Korean media say that "satellites have tracked a special North Korean train, the usual form of transport for Mr. Kim, entering Chinese territory.

If confirmed, it would be his second trip to Beijing in less than a year - an unheard-of flurry of diplomacy for a notoriously travel-shy figurehead.

The reports are impossible to verify, but they come amid growing signs of Chinese anger with Mr Kim over last month's missile tests, and regional anxiety about his next move. Earlier this month, the South Korean president, Roh Moo-hyun, requested an emergency summit with Beijing's leaders.

The Guardian notes that there are increasing signs of a rift between China and North Korea, indicating Beijing's frustration with North Korea's brinksmanship diplomacy with the United States. "China's exports of rice, maize and wheat to North Korea have slumped by more than two thirds in the first seven months of this year.... South Korea's Chosun Ilbo newspaper has reported a "significant decline" in oil exports. Chinese financial institutions are also said to have cooperated with US moves to freeze North Korean accounts."

The Korea Times reports that a South Korean official dismissed reports of Kim's trip to Beijing, saying that "as of now, we do not have any evidence." However, the International Herald Tribune reports that Kim Seung Kyu, the director of South Korea's National Intelligence Service, told South Korea's National Assembly in a closed-door briefing Monday that "the possibility of a nuclear test is always open" for North Korea. It was the first time that South Korean officials publicly acknowledged that North Korea was capable of a nuclear test.

"North Korea is believed to have facilities for a nuclear test," Kim was quoted as saying by Shin Ki Nam, head of the Intelligence Committee in the National Assembly. "The possibility of a nuclear test is always open as soon as Kim Jong Il makes a decision."

North Korea is not known to have performed nuclear tests on its territory, although some experts have said that a test in Pakistan in 1998 may have been conducted on North Korea's behalf in exchange for North Korean missile technology.

Although they were not as clear-cut about North Korea's test ability as Kim Seung Kyu, South Korean officials had previously said the North had conducted about 100 high-explosive tests since the 1990s, honing a technology crucial to successfully detonating a nuclear bomb.

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Kim stressed that his intelligence agency had no indication of an imminent test. The IHT noted that South Korean officials privately admit that their ability to monitor North Korean tests is largely based upon intelligence gathered by the United States.

The Associated Press writes that American and Japanese media reported earlier this month "that intelligence agencies were monitoring suspicious activity at a suspected North Korean underground nuclear test site, detecting moving vehicles and cables that could be used to connect the test site to aboveground diagnostic equipment." While experts believe North Korea has the material to make atomic weapons, no test that would prove the theory has yet been detected. In anticipation of a possible test, AP reports that a major earthquake center in South Korea has become a key observation post.

The Korea Earthquake Research Center recently was put on 24-hour watch as fears grew about a possible test. The Defense Ministry sent soldiers to scrutinize the center's wall of video screens, which display skittering graphs of data from some 90 seismic stations across South Korea. Alert systems have been installed to link government institutions with the earthquake center 100 miles south of Seoul. ...

The most reliable means of confirming a nuclear test would be from infrasound - ultra-low noises from an explosion below the range of human hearing. ...

But even a blast as powerful as a nuclear explosion could be difficult to immediately confirm if the North thoroughly seals the underground site, Chi said.

So the center can also measure seismic tremors, although they would be less conclusive, Chi said. If suspicious tremors were detected, experts would evaluate the data and determine whether they showed a nuclear blast or a natural earthquake. The process would take two to three hours.

In an editorial, the South Korean newspaper Chosun Ilbo notes that the government's admission about a possible North Korean nuclear test is a marked departure from its usual optimistic stance, and such a change may be cause for serious concern.

In July, when the entire international community was alerted to the North's impending missile tests, a key government official said it wasn't missiles but a satellite the North was preparing to launch. If even this government thinks there is half a chance of a nuclear test, the situation must be grave indeed. ...

The government insists on dismantling the nation's security structure while acknowledging that the North may well be about to conduct a nuclear test; the reason must be one of two. Either it is the belief that the North's nuclear weapons will never ever target the South so there is no need to worry. That logic calls for entrusting our security to the goodwill of the same North Korean regime that turned the country into a sea of blood five decades ago. The other is a mindset that doesn't see much wrong with turning our country over to North Korea. A nation that entrusts this government with its security lives dangerously.

However, Reuters reports that US Secretary of Defense Donald Rumsfeld told reporters that "the real threat that North Korea poses in the immediate future is more one of proliferation than a danger to South Korea."

"I don't see them, frankly, as an immediate military threat to South Korea," Rumsfeld said, noting South Korea's improved military capability as well as what the defence secretary described as a deteriorated condition of North Korea's forces.

Asked if North Korea's offensive missile capability is more of a threat to the United States than to South Korea, he said he did not know.

In a July article for the Korean citizen-journalism news site OhMyNews, Kim Tae Kyung argues that North Korea's missile tests are largely a diplomatic ploy to promote talks with the United States, and should be of limited concern to South Korea. A more pressing concern, he writes, is Japan's response to North Korea's actions.

...This event should be an issue between North Korea and the U.S. Of the many concerned countries, Japan has taken the hardest stance in response to North Korea's missile launch. Indeed, Japan acts as if it had been attacked by North Korea.

Japan's reactions to North Korea's missile tests are quite furious. Japan has not hesitated to provoke South Korea and China, and has made a huge issue out of the possible threat posed by North Korea. If Japan does not deal with tensions or conflicts with its neighboring countries in a well-measured and serious manner, it should not be considered a real member of the Northeast Asian region.

However, in a response also published by OhMyNews, Leif-Eric Easley writes that labelling the North Korean [DPRK] tests as "an issue between North Korea and the U.S." is misleading, and smacks of a nationalist response.

To suggest that the missile tests are not an issue between China and DPRK is to fail to recognize those countries' complex relationship. To suggest that the missile tests are not an issue between Japan and DPRK is to disregard Tokyo's security concerns. And to suggest that the missile tests are not an issue between South Korea and DPRK is to suggest that Seoul shirk its responsibility in dealing with North Korea and abdicate provision of its national security to the United States. Clearly this does not make sense. North Korea's weapons programs are a concern for regional stability, and thus an issue for all regional actors with interests for stability, requiring multinational coordination and resumption of the Six Party Talks as soon as possible.

If South and North Korea want to someday unify into a single peaceful and prosperous nation, Pyongyang's provocative activities are very much Seoul's concern. Americans and Japanese need to be convinced that South Koreans agree with this, at which point Washington and Tokyo should be more supportive of Seoul's vision for peace and prosperity on the Korean Peninsula. This process is not helped when Korean nationalism distorts the position of other countries.

Regardless of the political implications, the most immediate problem caused by a nuclear test may prove to be environmental. OhMyNews reports that North Korea may find it challenging to find a suitable nuclear test site within its borders.

According to an analysis by Satoshi Morimoto of Takushoku University, "carrying out nuclear tests inside North Korea would be an extremely sticky action. That is because this kind of nuclear testing could only be carried out underground. There is absolutely no way they could do it in the air or above ground."

But he also pointed out that an underground nuclear test would be challenging. Such a test would require 50 sq. km (19.3 sq. miles) of desert to avoid damaging aquifers. As North Korea has a very abundant system of aquifers, an underground nuclear test would disperse radioactive materials into the water supply for the whole of the Korean peninsula. Later, the radioactive elements would flow out into the Sea of Japan.

"As a consequence," Mr. Morimoto said, "if there were any underground nuclear testing on the Korean peninsula, it would not be just the ecosystem, but also the topography of the land that would be damaged."

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Feedback appreciated. E-mail Arthur Bright.