N Korea's Kim Jong-un oversees missile launching drill

Kim said "checking the reliability and rapid ​response of the components ‌of the DPRK's nuclear deterrent on a ​regular basis... are just a responsible ‍exercise," as the country "is facing various security threats", using North ​Korea's ​official ​name, Democratic People's Republic of ​Korea (DPRK).

Kim affirmed that North Korea would keep devoting all its efforts to developing its nuclear combat force, KCNA said.

North Korea is under heavy international sanctions imposed over its nuclear weapons and ballistic missile programs that were developed in violation of UN Security Council resolutions.

Experts and international officials say the sanctions have lost much of their bite amid growing economic, military and political support from Russia and China.