North Korean leader Kim Jong Un said his country would soon conduct a nuclear warhead test and a test launch of ballistic missiles capable of carrying nuclear warheads, the North's official KCNA news agency reported on Tuesday.
Such tests would be in defiant violation of United Nations sanctions that were recently strengthened with the backing of China, North Korea's chief ally.
Kim made the comments as he supervised a successful simulated test of atmospheric re-entry of a ballistic missile that measured the "thermodynamic structural stability of newly developed heat-resisting materials", KCNA said.
"Declaring that a nuclear warhead explosion test and a test-fire of several kinds of ballistic rockets able to carry nuclear warheads will be conducted in a short time to further enhance the reliance of nuclear attack capability, he (Kim) instructed the relevant section to make prearrangement for them to the last detail," the agency said.
South Korea's defense ministry said there were no indications of activities at the North's nuclear test site or its long-range rocket station, but that North Korea continues to maintain readiness to conduct nuclear tests.