War Games, Who's Playing

North Korea has kept promise to the international community and carried out its first underground nuclear test.

This comes after South Korean troops fired warning shots at soldiers from the North when soldiers crossed into the demilitarised zone amid rising tension.

Last Friday, the UN Security Council urged the N Korea not to undertake such an exercise and warned of unspecified consequences if it did.

According to North Korea's Korean Central News Agency, the test was "conducted with indigenous wisdom and technology 100 per cent."

The agency added: "It marks a historic event as it greatly encouraged and pleased the KPA (Korean People's Army) and people that have wished to have powerful self-reliant defence capability."

A US official said North Korea gave China a 20-minute warning of its test and China immediately told the United States, Japan and South Korea.

North Korea is believed to have enough fissile material to make six to eight nuclear bombs but, according to experts, probably does not have the technology to devise one small enough to mount on a missile.

South Korea said a tremor of magnitude 3.58 to 3.7 was detected in North Korea in the early hours. The US Geological Survey said however that it was not aware of the kind of seismic activity expected from such a test.