Democratic People's Republic of Korea launches a long range rocket launched into the air in this file still image taken from KRT video footage, released by Yonhap on February 7, 2016. [Photo/Agencies]

PYONGYANG -- Top leader of the Democratic People's Republic of Korea (DPRK) Kim Jong Un 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," the official KCNA news agency reported Tuesday.

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.