Seoul: Mercurial North Korea`s nuclear threat has reached an "alarming level" and it is now trying to miniaturise weapons to improve their mobility and impact, a South Korean government official said.
A US think-tank has also said satellite images taken last week showed that construction or excavation activity was taking place at the North`s main Yongbyon nuclear complex.
News that the North was pushing ahead with its nuclear plans in defiance of international pressure comes as Pyongyang, which has just recently set in motion a father-to-son power transition, has said it wants to return to stalled nuclear talks.
"We have judged that North Korea is currently operating all its nuclear programmes, including highly enriched uranium processing and the nuclear facility in Yongbyon," said Kim Tae-hyo, the President`s secretary for national strategy, according to the JoongAng Daily on Wednesday.
Even though it has exploded nuclear devices, North Korea has not shown it has a working nuclear bomb. Experts say they do not believe it has the ability to miniaturise an atomic weapon to place on a missile.
Under an earlier aid-for-disarmament agreement, the reclusive North began to close down Yongbyon, which when fully operational can produce enough fissile material for one nuclear bomb a year.
Last year, Pyongyang announced that in the face of US’ hostility it would restore parts of the plant, a year after blowing up the complex`s cooling tower in what it said was a display of its commitment to nuclear disarmament.
"Their nuclear programme is evolving even now at a very fast pace," Kim told a forum on the future of Northeast Asia, adding the North`s nuclear threat had reached an "alarming level”.
North Korean Vice Foreign Minister Pak Kil-yon told the UN General Assembly last week that Pyongyang would bolster its "nuclear deterrent" in response to the threat posed by the United States, but promised never to use its atomic arsenal to attack or threaten any nation.