China is a permanent member of the Security Council.
South Korea, still technically at war with the North after the 1950-53 civil war ended in a mere truce, said the size of the seismic activity indicated a nuclear explosion slightly larger than the North’s two previous tests at 6-7 kilotons, although that is still relatively small. The Hiroshima bomb was around 20 kilotons.
The U.S. Geological Survey said that a seismic event measuring 5.1 magnitude had occurred on Tuesday, with North Korea later confirming the nuclear test.
“It was confirmed that the nuclear test that was carried out at a high level in a safe and perfect manner using a miniaturized and lighter nuclear device with greater explosive force than previously did not pose any negative impact on the surrounding ecological environment,” KCNA said.
Despite China’s tame response, it likely to be a major embarrassment for Beijing, the North’s sole major economic and diplomatic ally.
“The test is hugely insulting to China, which now can be expected to follow through with threats to impose sanctions,” said Mark Fitzpatrick of the International Institute for Strategic Studies think tank.
North Korea trumpeted the announcement on its state television channel to patriotic music against the backdrop of an image of its national flag.
It linked the test to its technical prowess in launching a long-range rocket in December, a move that triggered the U.N. sanctions, backed by China, that Pyongyang said prompted it to take Tuesday’s action.
The North’s ultimate aim, Washington believes, is to design an intercontinental ballistic missile capable of carrying a nuclear warhead that could hit the United States. North Korea says the programme is aimed merely at putting satellites in space.
North Korea used plutonium in previous nuclear tests and prior to Tuesday there had been speculation it would use highly enriched uranium so as to conserve its plutonium stocks as testing eats into its limited supply of the material that could be used to construct a nuclear bomb.