"They want to use Yongbyon as leverage to get bilateral talks with the United States," said Selig Harrison, a US scholar who is just back from a visit to the North Korean capital where he held discussions with Kim Kye-gwan, Pyongyang's top negotiator at the stalled six-party talks on its nuclear ambitions.
With Korea stating that it would unload fuel rods, it brings into question the country's nuclear weapon capability once again.
On Saturday Harrison said: "The removal of the fuel rods is a significant new development because it underlines that North Korea is enhancing its weapons capability.
"Every time they unload it, they are getting a new increment of plutonium to be reprocessed and they are adding to the number of weapons that they could make."
Speaking to a Beijing news agency, Harrison quoted Kim as saying: "If Washington conceded the face-to-face talks it has long resisted, both sides could put whatever they've got on their minds on the table".
He said Kim had also said: "We want evidence that the US is giving up its hostile 'regime change' policy towards Pyongyang. I'm optimistic that the Bush Administration will climb down in the near future."
However, the message was clear according to Harrison: "Kim did make clear that the purpose of unloading the fuel was to obtain more plutonium for nuclear weapons."
Harrison spent six hours in discussions with negotiator Kim during the visit, and was told he was the first US scholar to visit North Korea this year.
It is not the first time that North Korea has extracted rods from its Yongbyon reactor. Fuel rods were extracted in May 2005, according to officials.
Proliferation experts said this could eventually provide enough material for another two or three atomic bombs.
Six-party talks broke down in November last year after North Korea refused to participate in protest at a US clampdown on its international financial dealings.