By Paul Reynolds
World affairs correspondent BBC News website
North Korea's main reactor at Yongbyon, source of plutonium
The fresh wind helping to set new courses for US diplomacy sees a direct meeting between American and North Korean diplomats in New York on Monday and Tuesday.
The meeting - between the main negotiators, Assistant Secretary Christopher Hill for the US and Vice-Foreign Minister Kim Kye-gwan for North Korea - is the first bilateral contact at this level for many years.
It has long been sought by North Korea, though the US side prefers to stress that it is simply "embedded" in the wider six-country talks.
If all goes well, US Secretary of State Condoleezza Rice is expected to go to Beijing in April for a meeting to be attended by the North Korean foreign minister as well.
The development comes in the middle of a new row about the reliability of US intelligence on North Korea. Doubts are being thrown on US assessments that it tried to enrich uranium, the claim that broke up a 1994 agreement in which North Korea promised to give up its nuclear ambitions.
The New York meeting follows the six-party agreement reached in Beijing on 13 February, which has similarities to the 1994 deal. North Korea has agreed to freeze and then disable its nuclear plants in exchange for aid and other benefits.
The broad agenda for the meeting was contained in the 13 February agreement itself: "The DPRK [North Korea] and the US will start bilateral talks aimed at resolving pending bilateral issues and moving toward full diplomatic relations.
"The US will begin the process of removing the designation of the DPRK as a state-sponsor of terrorism and advance the process of terminating the application of the Trading with the Enemy Act with respect to the DPRK."
Nobody expects all this to be done in New York. The "pending bilateral issues", for example, include several delicate problems.
The most difficult is the export of North Korean missile technology. This was not covered in the February agreement. However it is already subject to United Nations sanctions and these remain in force.
On the other hand, the problem of the North Korean counterfeiting of US dollars, which led to North Korea accounts in the Banco Delta Asia in Macau being suspended, does look like being resolved soon. Mr Hill has said that the US Treasury is "now prepared to resolve the Banco Delta matter".
The new momentum over North Korea has come about partly because US foreign policy has gone through a shift recently and also because North Korea has found itself more isolated, especially from China, following its nuclear test last October and the subsequent Security Council sanctions.
That there has been an American shift can be seen in the critical comments made about the February agreement by the former US ambassador to the UN John Bolton.
In an interview with Bloomberg, he said that, by accepting North Korean pledges, the Bush administration had "abandoned the principles it pursued for much of its first several years in office".
But Democrats, who now control both houses of congress, are delighted. The Chairman of the House International Relations Committee Tom Lantos stated: "Too often, the wise words and sound counsel of America's top diplomats have been drowned out by the strong unilateralist voices echoing through the hallways of the White House."
One part of the February agreement is that North Korea has to declare all its nuclear programmes.
There has been a flurry of interest this past week in the extent to which it has developed uranium enrichment and its declaration on this will be watched with interest.
The Bush administration used an alleged North Korean secret uranium enrichment programme to break away from the 1994 agreement reached by the Clinton presidency.
However, at a congressional hearing on 27 February, the chief US intelligence officer for North Korea, Joseph DeTrani, said that while there was "high confidence" that North Korea had acquired enrichment equipment, the US now had only "mid confidence" about its use of such materials.
Bush administration critics have seized on this to say that there was therefore no need to have departed from the 1994 agreement. Administration officials countered by saying that North Korea had admitted to the enrichment activity, in turn denied by the North.
The 1994 agreement was designed to stop the North's production of plutonium, the alternative route to a nuclear explosion, and it was plutonium that it used in its test in October.
But again, questions are being asked about the use of intelligence. David Albright, a former UN inspector and head of the Institute for Science and International Security, has written a paper on North Korea questioning the earlier US assessment on its enrichment work.
"The intelligence community conducted this assessment at the same time it produced a number of flawed assessments about Iraq's WMD program, which alone should trigger concern about past assessments of North Korea's centrifuge program," he wrote.
The New York Times has pointed up a new caution in US intelligence procedures, noting that one of the main critics of the intelligence on Iraq, Thomas Fingar, is now in charge of analysis for the office of the director of national intelligence.