North Korea ran simulated nuclear counterstrikes against unspecified foreign enemies on Monday, according to state media. 

The rocket launches were conducted under the supervision of supreme leader Kim Jong Un at an undisclosed location within the small region surrounding the capital city of Pyongyang.

Missiles fired Monday traveled over 300 kilometers and successfully struck a targeted island in the Sea of Japan.

The nuclear counterstrike simulation marked the debut of ‘Haekbangashoe’ — the hermit kingdom’s ‘nuclear trigger’ — and proved the efficacy of the ‘system of command, management, control and operation of the whole nuclear force,’ according to state news.

North Korea has claimed the 600mm multiple rocket launchers used in the Monday operation are capable of firing nuclear warheads.

Last week, North Korea conducted a separate series of military exercises over the Yellow Sea, testing a ‘super-large warhead’ for cruise missiles and anti-aircraft missiles.

Kim Jong Un promised a ‘death blow’ to any foreign nation that transgresses against North Korea while speaking at the Kim Jong-il University of Military and Politics earlier this month.

‘[Kim Jong Un] said that now is the time to be more thoroughly prepared for a war than ever before and that the DPRK should be more firmly and perfectly prepared for a war, which should be won without fail, not just for a possible war,’ North Korean state media reported. 

On Wednesday, U.S. Ambassador to the United Nations Linda Thomas-Greenfield said that the nation intended to create new mechanisms for monitoring the development of nuclear capabilities in North Korea.

‘I look forward to engaging with both the Republic of Korea and Japan, but like-minded (countries) as well, on trying to develop options both inside the U.N. as well as outside the U.N. The point here is that we cannot allow the work that the panel of experts were doing to lapse,’Thomas-Greenfield said to an audience in South Korea.

Republic of Korea is the official name of South Korea.