No surprise that, ‘North Korea delays nuclear talks’:

North Korea blamed war games between South Korea and the United States on Monday for a delay in resuming six-party talks on its nuclear weapons programs, but said negotiations could resume in the week of September 12.

However, the ‘war games’ (i.e., joint military exercises) were planned far in advance, and NK knew about them before the previous round of talks, so that is unlikely to be the actual reason for delaying talks.

Another possibility:

…analysts say Pyongyang may want to stall the talks so it can assess the outcome of Chinese President Hu Jintao’s visit to Washington next week.

Not listed in the media that I saw is what may be the most likely reason; NK is doing damage assessment on the recent admission by Pakistan:

Disgraced Pakistani scientist AQ Khan supplied North Korea with centrifuges and their designs, President Pervez Musharraf has confirmed… It is the first time Pakistan has given details about the type of technology Dr Khan transferred to Pyongyang… “Yes, he passed centrifuges - parts and complete. I do not exactly remember the number,” President Musharraf told Kyodo. [emphasis added]

Pakistan stressed that Khan didn’t give NK plans on how to construct a Uranium bomb, but only the enrichment technology. In reality, it’s a moot point, since Uranium bombs are much simpler devices to construct; the hard part is enrichment. On the other hand, Plutonium enrichment is relatively much easier, while constructing the detonating mechanism is much more difficult. If North Korea can construct a Plutonium bomb (not proved or disproved at this point), then they can certainly build a Uranium device if they have access to enriched material.

Looking back to North Korea’s effusive denials, first any hidden nuclear program, then a Uranium program, their insincerity in negotiating becomes all the more clear. Good luck Mr. Hill!