North Korean top leader Kim Jong Un has said his country will conduct a nuclear warhead explosion test and a test-fire of ballistic rockets able to carry nuclear warheads "in a short time."

朝鲜最高领导人金正恩表示，朝鲜将“很快”进行一次核弹头爆炸试验以及试射可以携带核弹头的弹道火箭。

The official KCNA news agency reported Kim made the remarks when he guided an environmental simulation for reentry into atmosphere of the warhead tip of a ballistic missile, the report said.

The simulation was conducted to "verify the thermodynamic structural stability of newly-developed heat-resisting materials under the high pressure and thermal flow caused by aerodynamic heating" when a ballistic rocket reenters the atmosphere, the KCNA said, adding that the test results met all technical parameters.