North Korean leader Kim Jong Un oversaw salvo launches of the country’s "super-large" multiple rocket launchers in what state media presented as simulation drills of a nuclear counterattack against enemy targets, state media revealed Tuesday.

The day prior, the South Korean and Japanese militaries reported suspected launches of artillery and ballistic missiles from the north. Pyongyang subsequently confirmed it tested new systems including 600mm multiple rocket launchers, said to be capable of delivering tactical nuclear warheads.

State media referred to the United States and South Korea, which have been conducting a series of joint military exercises over many months, as "warmongers" while describing the necessity of exercises focused on nuclear counterattack.

Kim has described that the north's new rocket launchers are as accurate as a "sniper's rifle". Kim observed the exercises from an observation post, a new set of photos released by KCNA shows.

According to a state media description, as cited in AP:

It said the rockets flew 352 kilometers (218 miles) before accurately hitting an island target and that the drill verified the reliability of the "system of command, management, control and operation of the whole nuclear force."

Part of the drill included a salvo of missiles sent toward "the potential enemy" which included targets on and outlying island with a range of just over 350km.

US officials have previously indicated the recent spate of more aggressive statements from Kim should be taken seriously.

"While the officials added that they did not see an imminent risk of a full-scale war on the Korean Peninsula, Mr. Kim could carry out strikes in a way that he thinks would avoid rapid escalation," a NY Times report issued early this year said.

All of this is said to be part of Kim's new policy of "open hostility" in response to US provocations on the peninsula, including starting last summer the docking of a US nuclear submarine at a South Korean port.