Leader Kim Jong Un attended the launch, which took place on Wednesday, the Korean Central News Agency (KCNA) said.

The agency said the drills were aimed at warning North Korea's enemies of Pyongyang's "counterattack capability in any space and the readiness of its various nuke operation means".

Attending the drill, Kim said it was the responsibility of North Korea's nuclear armed forces to "defend the national sovereignty and security".

"Powerful striking ability", he said, served as "the most perfect deterrence and defence", KCNA said.

Images in North Korean state media showed Kim, flanked by officials, sporting binoculars and watching a missile strike and destroy a small building on a nearby island.