The agreement by North Korea to dismantle its nuclear facilities by the end of the year represents a major step forward in the long, tortuous process of six-party negotiations.
By Gordon Corera
Security correspondent, BBC News
What prospects for peace on the Korean peninsula?
But even the most optimistic experts believe there is some distance still to travel.
Much of the focus has been on the detail - the "nuts and bolts" of implementation, as US negotiator Christopher Hill put it, and the journey of the coming months towards completion of the deal is unlikely to be without bumps along the road as some of the key details are worked through.
The agreement sets out a timetable for Pyongyang to declare and disable its nuclear facilities. A team of experts led by the US is expected to arrive in a matter of weeks to prepare this process.
North Korea has already suspended activity at its key Yongbyon plant - but actual disablement is a much bigger step.
The team are likely to survey the site and assess the different possibilities for disablement by looking at which equipment should be dismantled or broken up, a technical matter requiring considerable expertise.
Demands of deal
"There are many steps left to be taken," argues Andreas Persbo, an arms control researcher at Vertic, a think tank which specialises in verification issues.
If there is full disclosure and disablement it will be seen widely as representing a much needed victory for the Bush administration
"While some progress is likely before the New Year, the issue will be far from resolved by then. For instance, it is not enough to simply remove the irradiated fuel from the reactor. It would need to be either transported out of the country, or destroyed in some manner in North Korea and under international supervision.
"Also, it is not enough to maintain a verification presence at the nuclear centre in Yongbyon alone. North Korea needs to provide sufficient access to individuals, documentation, equipments and facilities, so that all outstanding questions, including the one on the extent of North Korea's uranium enrichment programme, can be satisfactorily answered."
Disclosure remains the major US concern. Washington is especially keen to make sure that North Korea is open about any uranium enrichment activity it has undertaken in parallel to the reprocessing activity centred on Yongbyon.
It was intelligence of a secret North Korean enrichment programme that led to the collapse of the previous nuclear accord with the US, agreed in 1994.
North Korea was provided with centrifuges by Pakistani scientist AQ Khan and also appeared to be shopping for parts in the black market.
Since disclosure of this activity, US officials have acknowledged that their confidence in how far the North Koreans had progressed was limited, making disclosure all the more important.
This issue has been further complicated by the swirl of rumour surrounding the Israeli attack on a Syrian facility on 6 September. There have been unconfirmed claims that the target was some kind of nuclear facility which North Korea was involved in.
A successful deal could have implications for Iran's treatment
A fully fledged Syrian programme is considered unlikely but one theory circulating was that North Korea might be transferring elements of its nuclear programme such as enrichment technology to the Syrians in order to hide and protect it from any nuclear deal struck under the six-party talks.
However, no-one publicly is confirming that this was indeed the target, and hiding material would be a risky move by Pyongyang.
The last round of six-party talks was delayed by the Israeli strike, which provided grist for the rumour mill but which clearly did not derail the North Korean deal. An interesting question is how far North Korea will be expected to disclose any possible co-operation with Syria as part of an agreement.
North Korea will also be looking to ensure that it receives what is promised under the deal - including shipments of fuel and the lifting of various sanctions by the US, including Pyongyang's presence on the list of state sponsors of terrorism.
Implications for Iran
A few voices in Washington have been critical of the entire deal. John Bolton, former US ambassador to the United Nations, is amongst those, arguing that countries should not be offered incentives or deals to give up their programmes.
Nevertheless, if there is full disclosure and disablement it will be seen widely as representing a much needed victory for the Bush administration.
But it may also raise further questions as to whether the other great proliferation challenge of the moment - Iran's nuclear programme - can also be dealt with by patient negotiation.
The two situations are very different - North Korea already had the capacity to produce material for weapons and had carried out a test, whereas Iran is instead seeking the capacity to produce fissile material (for peaceful reasons, it maintains).
The regional security situation and relative strength of the two countries also differ significantly, as do the internal political dynamics.
That all makes the Iranian challenge arguably much more difficult but if by the end of the year the deal with North Korea has held, that will at least represent one major accomplishment that few would have predicted a year earlier.