The North's response came in mid-afternoon, in a 1, 000 word statement from its highest decision-making body, the National Defense Commission.

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On Jan. 24, the National Defense Commission, North Korea's most powerful body, said "a nuclear test of higher level" would be carried out.

WSJ: Pyongyang Tests Nuclear Device

Ri Yong Ho was appointed vice marshal and vice chairman of the National Defense Commission, the body considered the most powerful in North Korea.

WSJ: Dictator's Death Stokes Fears