At a ceremony on Wednesday, Kim gave a speech touting the new 600-mm multiple launch rocket system as unique in the world and said it is "appropriate for a special attack, that is, for accomplishing a strategic mission," the Korean Central News Agency (KCNA) reported, using a common euphemism for nuclear use.

He insisted the weapons system was for "deterrent" use against enemies he did not name. South Korea remains the North's primary adversary.

"When this weapon is used actually, no force would be able to expect God's protection," Kim said, according to KCNA. "It is really a wonderful and attractive weapon."

When Kim toured the factory producing the rockets last month, South Korean officials and analysts said they could be used against Pyongyang's southern neighbour.

Seoul is less than 50 kilometres (30 miles) from the intra-Korean border at its nearest point.

North Korea is still technically at war with the South and "saturation" strikes by its vast artillery arsenal have long been believed to be central to its strategy should conflict break out.

Pyongyang has significantly stepped up missile testing in recent years.

Analysts say this drive is aimed at improving precision strike capabilities, challenging the United States as well as South Korea, and testing weapons before potentially exporting them to Russia.

Pyongyang is set to hold a landmark congress of its ruling party in early 2026 -- its first in five years.

Economic policy, as well as defence and military planning, are likely to be high on the agenda.

In another development, Kim's powerful sister, Kim Yo Jong, said Thursday she "highly appreciates" South Korea's pledge to prevent a recurrence of drone incursions into the North.

North Korea claims it shot down a surveillance drone last month, an incident that threatened to blight South Korean President Lee Jae Myung's efforts to improve ties with the North.

Seoul's Unification Minister Chung Dong-young expressed "deep regret" over this last week.

"I highly appreciate Chung Dong-young, minister of unification of the ROK, officially acknowledged the ROK-born drone's provocative intrusion into the airspace of our country, expressing regret once again and willingness to prevent a recurrence," KCNA quoted Kim saying, the Yonhap news agency reported.