North Korean leader Kim Jong Un supervised missile tests that simulated nuclear counterstrikes against U.S. and South Korean forces, state media said.

The tests of short-range ballistic missile systems from North Korea’s eastern coast were detected by South Korea’s military the day before.

North Korea’s official Korean Central News Agency (KCNA) said the tests involved a mobile ballistic missile system apparently modeled after Russia’s Iskander.

Russia and North Korea have been cooperating in Moscow’s war against Ukraine. Pyongyang has provided Russia with troops and munitions.

KCNA also said North Korea was testing 600-millimeter multiple rocket launchers that South Korean officials classify as ballistic due to their self-propulsion and guided flight.

Both are part of a growing lineup of weapons systems that the North says could be armed with “tactical” nuclear weapons for battlefield use.

The tests were intended to train military units operating missile and rocket systems to more effectively execute attacks under the North’s nuclear weapons control system and ensure a swift response to a nuclear crisis, KCNA said.

“The US and its vassal states are staging a series of nuclear operation drills on the Korean peninsula and in its vicinity after making a nuclear war against the Democratic People’s Republic of Korea a fait accompli and opening to the public an extremely adventurous scenario for a nuclear war,” KCNA said.

“This reckless act of aggravating the situation requires that the armed forces of the DPRK maintain a rapid reaction capability and thoroughgoing war posture.”

This is a developing article and more information will be added soon.

This article uses reporting by The Associated Press.