North Korean leader Kim Jong Un on Thursday unveiled a new facility to make nuclear fuel, describing it as a “historic” event in upgrading the country’s forces.
The facility, at an undisclosed location, would deliver “more sophisticated technology”, the Korean Central News Agency noted but did not reveal any details of its capabilities.
The South Korean military assessed the site as a uranium-enrichment plant and said it was closely coordinating with the US to monitor North Korean nuclear activities.
Mr Kim, accompanied by officials from the Nuclear Weapons Institute, visited the factory to learn about its operations and discuss its long-term production plan.
The North Korean leader said that production capacity for weapons-grade nuclear material had "more than doubled" over the past five years.
“We have confirmed the order of priority for implementing the ambitious future plan designed to beef up our state’s nuclear forces at an exponential rate as well as a requisite guarantee for the purpose,” he said.
Pictures released by state media showed Mr Kim standing between rows of cylindrical centrifuges for highly enriched uranium.
One image showed him speaking with senior officials in a meeting room, where a blurred graphic depicting a cone-shaped object was spread across a table. It wasn't immediately clear whether it showed a warhead design.
North Korea is known to possess at least three uranium-enrichment facilities – in Yongbyon and Kusong in North Pyongan province and Kangson in Nampo.
Mr Kim said the urgency for bolstering the country's nuclear war deterrent, both in quality and quantity, had grown because of confrontations with "the most ferocious enemies", an apparent reference to the US and South Korea.
Analysts said Mr Kim's visit appeared aimed at reinforcing North Korea’s negotiating position ahead of potential diplomatic engagement with China while justifying an acceleration of its nuclear build-up.
Chinese leader Xi Jinping is expected to visit later this month. A Chinese cargo plane arrived at the Pyongyang airport while North Korean authorities started preparations for the visit at Kim Il Sung Square, according to reports.
Chad O’Carroll, founder of NK News website, said Mr Kim’s site visit could be linked to Mr Xi’s potential trip to Pyongyang. He pointed out that before visiting Beijing in 2025, Mr Kim had inspected plans for a new intercontinental ballistic missile called "Hwasong-20”.
"The logic would be to demonstrate absolutely that denuclearisation is not possible, right on the eve of contact with the PRC," Mr O’Carroll said, using China's formal name, the People's Republic of China.
Lim Eul Chul, a professor at Kyungnam University’s Institute for Far Eastern Studies in South Korea, linked the site visit to Seoul’s pursuit of a nuclear-powered submarine and its talks with Washington over uranium enrichment rights, which he said Pyongyang could be using to justify accelerating its weapons programme.
"Even if South Korea does not proceed, the North will follow its own path, but such developments provide a convenient pretext to push its nuclear build-up faster and on a larger scale," Mr Lim said.
The unveiling of the latest facility came nearly two years after Mr Kim revealed another covert factory for uranium enrichment, in what was Pyongyang’s first public disclosure of such a facility since showing one at the Yongbyon nuclear complex to visiting American scholars in 2010.
Pyongyang is estimated by western intelligence agencies to possess nearly 50 nuclear warheads.
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