The outline deal was struck at the latest round of six-nation talks in Beijing, just when it seemed they were destined for collapse. Instead the participants - the US, Russia, the two Koreas, China and Japan - came up with what a Chinese spokesman called "the most important result since the six-party talks began" in August 2003.
In Washington, however, the reaction was more cautious, reflecting a deeply ingrained scepticism after more than a decade of pledges made and broken by the secretive and unpredictable regime in Pyongyang.
The agreement was "a wonderful step forward," President George Bush declared, but he warned that the North had to keep its promise. "The question is, will over time all parties adhere to it?" Mr Bush asked.
Christopher Hill, the chief US negotiator in Beijing, described the breakthrough as "a win-win situation". But the North should show it was sincere by shutting down its main nuclear facility at Yongbyon: "The time to turn it off would be about now," he said. Under the deal, North Korea has "committed to abandoning all nuclear weapons and existing nuclear programmes," according to a statement issued after the talks. Pyongyang is also promising to return "at an early date" to the Nuclear Non-Proliferation Treaty, and to re-admit inspectors.
It was North Korea's admission, in late 2002, that it was pursuing a clandestine uranium enrichment programme and the subsequent expulsion of inspectors from the UN's International Atomic Energy Agency that triggered the latest crisis.
Since then, Pyongyang is believed to have built at least one, and perhaps as many as seven or eight nuclear devices, using plutonium extracted from spent fuel rods from the experimental reactor at Yongbyon.
As its part of the bargain, the US has affirmed it has no nuclear weapons at its bases in South Korea and stated it has no intention of launching a nuclear or conventional attack. This is close to the mutual non-aggression pact long demanded by the North.
The statement sidesteps North Korea's demand to be given a light-water nuclear reactor, noting that this issue would be addressed "at an appropriate time". But the other five countries have undertaken to provide economic aid, while South Korea is offering to supply electricity across the militarised border that divides the Korean peninsula.
The challenge is to translate promises into deeds - a process that will start at the next round of talks, set for Beijing in November - and not only the US has misgivings. "Agreeing a common document does not mean that the solution to our problems has been found," said Kenichiro Sasae, Japan's top envoy to the talks.
"The devil is in the detail," said Wendy Sherman, a North Korea policy co-ordinator for the Clinton administration, which negotiated the last deal with Pyongyang in 1994. The agreement fell apart as Pyongyang continued to pursue nuclear weapons in secret and the US failed to provide promised civil nuclear facilities.
This time the omens appear brighter. The Bush administration is adopting a more flexible approach, dropping its earlier insistence that the North must halt its nuclear programme altogether before receiving any aid. For all the mixed signals from Pyongyang, Western experts believe the North now genuinely wants a deal, while Washington says it is ready to start normalising diplomatic relations.
But further surprises are possible. In the past the North has deliberately upped tensions by conducting ballistic missile tests. On other occasions, it has seemed to be preparing for a nuclear test. None has yet been carried out, but Pyongyang has flatly claimed that it has nuclear weapons.Reuse content