Describing the news as troubling and as a provocative act, senior US officials have called on the United Nations and China to step up the enforcement of sanctions against Pyongyang. But there's been little response so far from South Korea.
Presenter: Karon Snowdon
Admiral Michael Mullen, chairman, US joint chiefs of staff; Stephen Bosworth, US special envoy to North Korea; Kim Sung-hwan, South Korean foreign minister; Professor Lee Hung-Joon, international relations, Yonsei University
SNOWDON: A visiting US scientist was shown a small industrial scale uranium enrichment plant in North Korea's nuclear complex near Yongbyon and told it contained about 2000 centrifuges - a figure he couldn't confirm.
The senior military officer in the US, the chairman of the joint chiefs of staff, Admiral Michael Mullen, says the plant is part of the North's attempts to destabilise the region.
MULLEN: A country that is led by a dictator who constantly desires to destabilise the region and he's done that again certainly with this capability as well. And certainly the development of nuclear weapons is a huge concern for all of us - those in the region as well as those around the globe.
SNOWDON: The US special envoy on North Korea, Stephen Bosworth, happened to be in South Korea as the news broke.
He was overheard in Seoul agreeing with foreign minister, Kim Sung-hwan, that both governments have known about the enrichment plant for some time.
KIM: It's nothing new.
BOSWORTH: No, we've known about this for some time, but it's a very unfortunate development, but it's not a crisis.
KIM: Yes, it's not a crisis.
SNOWDON: South Korea's foreign minister, Kim Sung-hwan, speaking with US special envoy to North Korea Stephen Bosworth, who then left for Japan and China.
Professor in international relations at Yonsei University, Lee Jung-Hoon, takes a grim view of the North's actions.
LEE: This is really bad news for the non proliferation community trying to bring North Korea back to the six party talks because in fact it seems very clear North Korea is going in the opposite direction. In fact, North Korea is very much bent on having nuclear weapons and it's not just plutonium based but now it seems very clear they have a uranium based nuclear weapons programme as well.
SNOWDON: North Korea abandoned the six nation talks over a year ago and not long after tested its second nuclear bomb in violation of agreements to end its nuclear programme.
Later it announced it had the capability of enriching uranium for bombs and further raised tensions with the sinking in March of a South Korean naval vessel.
Stephen Bosworth believes the six party talks can still be revived if the North can prove it's serious about the process.
BOSWORTH: We do not at all rule out the possibility of further engagement with North Korea but we want that to take place under a proper set of conditions and in close coordination with our partners. I do not believe in engagement just for the sake of engagement.
SNOWDON: Professor Lee Jung-Hoon says the six party talks are a dead end and UN sanctions need to be enforced especially by China.
LEE: There's no way under the current circumstances, under the current environment. They can have 1,000 six party talks and nothing will be resolved. They are now lining up to have a third nuclear weapons test. And therefore the only real genuine way possible to get North Korea to give up its nuclear weapons programme is - number one - to get China on board and the international community has to speak in unison and the message has to be very clear that there will be severe penalty for North Korea for continuing with the nuclear weapons programme and that severe penalty has to be economic. But unfortunately the message is not being clearly delivered to North Korea because China and parts of South Korea continue to provide to North Korea based on a humanitarian basis or what have you. So they don't really feel the sense of urgency to give up their nuclear weapons programme. So, under the current circumstances, to expect something new out of North Korea is really being naive.