Seoul, South Korea - South Korea - North Korean leader Kim Jong-un conducted oversight tests of short-range ballistic missile systems, simulated nuclear power behaviors against us and South Korean forces, state media said Friday, and North Korean media said Friday that the North continued to blame its competitors for escalating tensions through their joint military exercises.

The report, published the day after the South Korean military launched multiple launches from North Korea's eastern coast, assessing that the tests could also be related to the country's arms exports to Russia during the Ukrainian war.

North Korea's official Central News Agency said Thursday's test involved a mobile ballistic missile system apparently modeled on the Russian iSkander and multiple 600mm rocket launchers, which South Korean officials classified as ballistic for their self-promotion and guidance of flights. Both are part of an increasingly large lineup of weapon systems, and the North says it can be equipped with "tactical" nuclear weapons for use on the battlefield.

The tests are designed to train missile and rocket systems operated by military units to perform attacks more effectively under the nuclear weapons control system in the north and ensure rapid response to the nuclear crisis, KCNA said.

The agency criticized the United States and its "vassal states" for expanding joint military exercises on and around the Korean Peninsula, which the North claimed was a preparation for a nuclear war and said Thursday's launch indicated a "fast counterattack posture" of its troops.

KCNA said Kim stressed the need to strengthen the role of his nuclear forces in stopping and war and called for continued efforts to improve combat readiness and precise strike capabilities.

The joint chief of staff of South Korea said that from 8:10 to 9:20 a.m. Thursday, multiple types of missiles were fired from the area near the eastern port city of Wangsang, which traveled about 800 kilometers (497 miles).

Co-leader spokesman Lee Sung Joon said North Korea's launch could be designed to test the performance of its exported weapons as the country continues to send military equipment and troops to Russia's war against Ukraine.

Japanese Defense Minister Gen Nakatani told reporters that none of North Korean missiles reached Japan's exclusive economic zone and that ships or aircraft in the area were damaged.

It was the first ballistic activity in the north since March 10, when it fired several ballistic missiles hours after the U.S. and South Korean forces began their annual military exercises and the country's sixth start of the race this year.

Tensions on the Korean Peninsula have escalated in recent months, with North Korean leader Kim Jong-un continuing to accelerate the development of his nuclear and missile programs and providing weapons and troops to support Russia’s war against Ukraine.

Thursday's press conference was in North Korean state media said Kim Jong Il urged ammunition workers to promote production of ammunition workers amid deepening consistency with Moscow.