A team of experts, led by America, started work on November 5th to disable three of North Korea's nuclear facilities at Yongbyon: the reactor, the nearby plant that fabricates natural uranium into fuel for the reactor core and the chemical reprocessing plant where bomb-usable plutonium is separated from the spent fuel-rods. The work should be finished by year's end, when North Korea is also supposed to have made a clean breast of other nefarious nuclear activities. Then talks among the six countries involved—including South Korea, Japan, China and Russia—can turn to dismantling Yongbyon, and to North Korea's promised disarmament.

But will North Korea really give up the estimated 50kg (110lbs) of separated plutonium (enough for at least 6-8 bombs) it is thought to have squirrelled away? By getting down, literally, to nuts and bolts at Yongbyon, the six-party process has got a crucial step further towards that disarmament goal than previous efforts. Under a 1994 deal with the Clinton administration, North Korea agreed merely to freeze operations at Yongbyon, while America, South Korea and Japan laboured to build two Western-designed, less proliferation-prone reactors as a huge bribe. The deal fell apart in 2002, when America confronted North Korea with evidence of its cheating: a parallel effort to produce enriched uranium, another possible bomb ingredient.

At six-party talks in February, North Korea accepted the equivalent of 1m tonnes of heavy fuel-oil (some of it in other forms of energy assistance) for disabling Yongbyon. Once disabled, says America's chief negotiator, it would take North Korea at least a year to get the plutonium-producing reactor up and running again.

Of course, with the nuclear stash he already has, North Korea's Kim Jong Il might not be fussed at such a delay. And much could go wrong from here. One difficulty lies in the six-party complexities. But other problems already loom.

It was a badly-behaving North Korea—in October 2006 it conducted a provocative bomb test—that persuaded the other five to back tough sanctions, helping the February deal to fruition. Now nuclear progress brings its own worries.

South Korea is straining to push through economic and other deals with North Korea, fearing that a speedy rapprochement between prickly Mr Kim and America will reduce its own leverage over the North. America worries that such generosity could weaken Mr Kim's incentive to stay on the nuclear straight and narrow. Japan, meanwhile, is anxious that America, in pursuit of nuclear progress, will remove North Korea from its terrorism blacklist before Mr Kim has come up with information Japan wants about its citizens abducted to North Korea in the past. It refuses to stump up towards energy aid, but may contribute to the disabling costs.

North Korea, though, still has to produce its list of weapons programmes (to include any uranium dabbling). A first draft is expected shortly. George Bush has said it must also include nuclear assistance Mr Kim has given to others. Some nuclear material was discovered in Libya several years ago of possible North Korean origin. And America and Israel reportedly think the list should also include Syria. An Israeli air raid in September is thought to have targeted a nuclear site—possibly a building to house a reactor—being built with North Korean assistance. Syria has bought missiles from North Korea, but both deny nuclear co-operation.

There might be more. Before talk of a Syrian connection, an article in the March issue of Arms Control Today by Siegfried Hecker and William Liou listed the many ways North Korea's nuclear expertise could be of use to Iran, which also has suspect nuclear ambitions. Mr Kim co-operates closely with Iran on missile development, and most recently supplied it with nuclear-capable missiles able to fly 2,500km (1,150 miles). He has also helped it build secretive underground tunnels.

A North Korean list devoid of all outside nuclear connections would be one damaging development; full disclosure could be another sort of bombshell.