Mr Ban also called on Russia - a member of the stalled six-party talks on North Korea's nuclear programme - to help bring Pyongyang back to the negotiating table.

BBC: Ban Ki-moon urges North Korea to end missile tests

The administration of former U.S. President George W. Bush scrapped a nuclear-freeze agreement with North Korea in 2002 over allegations that Pyongyang abrogated the pact by exploring uranium-enrichment activities.

WSJ: Clinton Praises China Stimulus, Has Hope for North Korea Relationship

The U.S. and other countries, most notably Korea's close neighbor Japan, are deeply worried by the North's long-range ballistic-missile program, which Pyongyang has put on hold but not abandoned.

CNN: ASIANOW - TIME Asia | Korea: Korea's Big Show

In Japan, the government convened a national security meeting soon after the test was detected, and later announced additional sanctions against the North, including a widening of entry ban for pro-Pyongyang ethnic Korean residents.

WSJ: North Korea Tests Nuclear Device

Turning to international news, experts tell Hong Kong's South China Morning Post that Beijing will verify the purpose of any bank accounts linked to North Korean leader Kim Jong-un before taking any action against Pyongyang.

BBC: China media: Political models

After the talks in Beijing ended, it offered to provide North Korea with aid for its bankrupt economy provided Pyongyang scrapped its nuclear-arms programme.

ECONOMIST: Dangerous and nuclear

South Korean President Lee Myung-bak has refused aid, trade and talks with North Korea until Pyongyang apologizes for its alleged sinking of a South Korean navy ship and shelling of Yeonpyong Island.

CNN: Why is North Korea willing to deal on nukes?

Rep. Bill Richardson, D-New Mexico, plans to arrive in North Korea on Sunday to meet with the Pyongyang government on issues including peace with South Korea, missing American soldiers, and the food shortage in North Korea.

CNN: U.S. diplomat plans visit to Korea

While Japan and South Korea indicated they might support a regional initiative to sway Pyongyang, China -- a key ally and aid donor to the North -- appeared to remain unconvinced.

CNN: N. Korea warns of nuclear conflict

The project has also attracted Andrei Lankov, a Seoul-based historian of North Korea who grew up in the Soviet Union and went to college in Pyongyang, the North Korean capital.

WSJ: Gulags, Nukes and a Water Slide: Citizen Spies Lift North Korea's Veil

Some of Mr Bush's officials are known to believe that the opening up of North Korea in recent months has been via a one-way street, with all the concessions going to Pyongyang.

ECONOMIST: Bush's Korean scepticism | The

For instance, when the US reacted to North Korea's 2006 nuclear and ICBM tests by reinstating the six-party talks in the hopes of appeasing Pyongyang, Iran learned that by exhibiting an interest in engaging the US on its uranium enrichment program it could gain valuable time.

CENTERFORSECURITYPOLICY: Israel and the Axis of Evil

In Washington, President Barack Obama's spokesman that "despite the harsh rhetoric we are hearing from Pyongyang, we are not seeing changes to the North Korean military posture, such as large-scale mobilisations and positioning of forces".

BBC: North Korea expands nuclear weapons programme

The US and North Korea's neighbours fear Pyongyang's ultimate goal is to put a nuclear warhead on a long-range missile that could target the west coast of the US, but it is not believed to have mastered the technology yet.

BBC: North Korea in nuclear warning after UN rocket resolution