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.
Despite its three nuclear tests and long-range rocket tests, North Korea is not believed to be close to manufacturing a nuclear missile capable of hitting the United States.
South Korea’s Yonhap news agency said Pyongyang had informed China and the United States of its plans to test on Monday, although this could not be confirmed.
When North Korean leader Kim, 30, took power after his father’s death in December 2011, there were hopes the he would bring reforms and end Kim Jong-il’s “military first” policies.
Instead, the North, whose economy is smaller than it was 20 years ago and where a third of children are believed to be malnourished, appears to be trapped in a cycle of sanctions followed by further provocations.
“The more North Korea shoots missiles, launches satellites or conducts nuclear tests, the more the U.N. Security Council will impose new and more severe sanctions,” said Shen Dingli, a professor at Shanghai’s Fudan University. “It is an endless, vicious cycle.”
But options for the international community appear to be in short supply, as North Korea is already one of the most heavily sanctioned states on earth.
Tuesday’s action appeared to have been timed for the run-up to Feb. 16 anniversary celebrations of Kim Jong-il’s birthday, as well as to achieved maximum international attention.