State media in North Korea reported on Friday that ruler Kim Jong Un had supervised a weapons exercise the previous day in which a volley of missiles was fired from rocket launchers.
This was intended as a show of force against South Korea, the reports said, and had used a launch control system which is part of the "state management system for nuclear weapons."
North Korea claims to have missiles equipped with tactical nuclear warheads that can be fired from multiple rocket launchers to hit targets throughout South Korea.
The exercise was also said to demonstrate North Korea's ability to launch a pre-emptive attack against South Korea in the event of a military threat from its enemies.
Pyongyang considers South Korea and the United States to be its main foes. South Korea's military detected the North Korean missile test on Thursday. Indications showed that at least 10 short-range ballistic missiles were fired eastwards towards the open sea.
South Korea held an air force exercise with several fighter jets near the border between the two countries on Monday after North Korea had announced a satellite launch. The launch, which was intended to put a military reconnaissance satellite into space, later failed.
The US and South Korea accuse North Korea of using technology directly related to its ballistic missile programme in its satellite launches in violation of UN prohibition resolutions. Depending on their design, such missiles can also be equipped with a nuclear warhead.
Tensions on the Korean Peninsula have increased significantly recently. North Korea has significantly stepped up its missile tests while South Korea and the US have expanded their military co-operation.