Kim Jong Un vowed an “exponential” increase in nuclear military capabilities as state media reported the North Korean leader visited a new atomic facility.

The nuclear-armed country is believed to operate uranium enrichment facilities at three sites — Yongbyon, Kangson and Kusong.

Kim on Wednesday went to a “newly-inaugurated nuclear materials production factory”, Pyongyang’s state-run Korean Central News Agency (KCNA) said.

KCNA reported that Kim noted an “ambitious future plan designed to beef up our state’s nuclear forces at an exponential rate.”

Rejecting pressure from the United States, North Korea insists it will not give up its nuclear arsenal, describing its path as “irreversible”.

While at the reported facility, Kim also said the “weapons-grade nuclear materials production capacity more than doubled during the past 5-year course.”

North Korea has conducted eight missile tests this year, which analysts say may reflect Pyongyang’s efforts to take advantage of eroding international norms to cement its nuclear status.

Although North Korea did not disclose the location, analysts said the facility was likely the newly completed uranium enrichment plant at Yongbyon.

Yang Moo-jin, former president of the University of North Korean Studies, said if the site is indeed verified to be at Yongbyon, it could also serve a propaganda purpose.

With Iran’s enriched uranium stockpile a key issue in US-Iran nuclear talks, North Korea appears to be “deliberately showcasing” its expanding nuclear capabilities to signal that denuclearisation is not up for negotiation with Washington, he added.

The key takeaway from Wednesday’s inspection is that North Korea is ramping up production of nuclear materials to meet growing demand, said Hong Min, an analyst at the Korea Institute for National Unification.

North Korea has already unveiled a large number of tactical nuclear weapons, he said, and as a result there is a “growing need to produce more nuclear warheads” for deployment on tactical missiles”.

Pyongyang withdrew from the Non-Proliferation Treaty in 1993 and has since conducted six nuclear tests, subjecting it to multiple United Nations resolutions, and is believed to possess dozens of nuclear warheads.