Kim also ordered the North Korean military to boost its readiness near the western maritime border with South Korea.

The report on the launches by the Korean Central News Agency (KCNA) on Thursday came a day after South Korea’s military said North Korea had fired multiple cruise missiles in waters off its eastern port of Wonsan. The test was Pyongyang’s sixth missile launch event of the year.

The KCNA report said Kim supervised the “evaluation test-fire of new-type surface-to-sea missile Padasuri-6 to be equipped by the navy”, and expressed “great satisfaction over the results of the test-fire”.

The missiles hit their intended targets after flying over the East Sea for 1,400 seconds, it said. The East Sea is known as the Sea of Japan internationally.

Kim also accused South Korea of frequently violating his country’s sovereignty by insisting on a “Northern Limit Line” (NLL), the maritime demarcation line between the two Koreas, and conducting maritime patrols and inter-diction of third-party ships, according to the KCNA. The North Korean leader also gave orders to his military to strengthen its readiness in the waters north of Yeonpyeong Island and to the west of the Korean peninsula, in the region of the NLL.

Waters near the NLL, which was drawn up by the United States-led United Nations Command at the end of the Korean War in 1953, have been the site of previous clashes between the two Koreas. In 2010, North Korea torpedoed a South Korean warship in the Yellow Sea, killing 46 Sailors, and fired a barrage of artillery shells at Yeonpyeong Island, killing four others.

According to the KCNA, Kim referred to the de facto border as a “ghost one without any ground in the light of international law”.

“It doesn’t matter how many lines exist in [North Korea’s] western sea, and what’s clear is that if the enemy violates what we consider as our maritime border lines, we will take that as a violation of our sovereignty and an armed provocation,” he was quoted as saying.

Kim also pledged that Pyongyang would “thoroughly defend our maritime sovereignty by force of arms and actions, not by any rhetoric”.

Earlier this year, the North Korean leader told his country’s rubber-stamp parliament that he would no longer recognise the NLL, and declared that Pyongyang was abandoning its longstanding goal of reconciliation with Seoul. He also said that if South Korea “violates even 0.001 millimetre of our territorial land, air and waters, it will be considered a war provocation”.

In a separate report, KCNA said Kim also inspected a “major” munitions factory and learned in detail about the modernisation of production.

During the visit, he stressed the factory’s role in bolstering North Korea’s armed forces and laid out tasks to improve the quality of munitions and increase production as “required by the prevailing situation and the developing revolution”, KCNA said.

Kim’s visit to the munitions factory comes as the US and its allies have accused North Korea of trading arms with Russia.

The White House said last month that Russia had recently used short-range ballistic missiles (SRBMs) sourced from North Korea to conduct strikes against Ukraine, citing newly declassified intelligence.