A senior South Korean official stated on Thursday that North Korea is operating four uranium enrichment facilities, corroborating external analyses suggesting the existence of several secret atomic sites in addition to the well-known facility near the capital, Pyongyang.

North Korea’s leader, Kim Jong Un, has advocated for a swift augmentation of his nation’s nuclear arsenal and recently asserted that these weapons would never be used as a bargaining tool in response to US President Donald Trump’s overtures.

Chung Dong-young, the South’s Unification Minister, noted that uranium enrichment centrifuges at the four sites, including the recognized site at Yongbyon, located about 60 miles from Pyongyang, are operational daily. He emphasized the critical need to halt the North’s nuclear ambitions.

Chung did not elaborate further on the location of the other, undeclared nuclear sites.

He spoke about the North with local reporters, according to his ministry.

A nuclear stockpile

Chung cited an assessment that the North possesses about 4,400 pounds of highly enriched uranium.

He first said that was based on intelligence but the ministry later clarified it was attributed to civilian experts.

If confirmed, the amount would also signal a sharp increase in North Korea’s stockpile of nuclear material.

In 2018, Stanford University scholars, including nuclear physicist Siegfried Hecker who had previously visited the Yongbyon complex, said the North had about 550 to 1,100 pounds of highly enriched uranium, sufficient for 25 to 30 nuclear devices.

Nuclear weapons can be built using either highly enriched uranium or plutonium, and North Korea has facilities to produce both at Yongbyon.

Last year, North Korea released photographs of what it said was a uranium enrichment facility, the first such disclosure since it showed the one at Yongbyon to Hecker and others in 2010.

The location and other details of the facility in the photographs remain unknown.

Foreign experts believe North Korea has built additional uranium-enrichment sites as Kim has been pushing hard to expand his nuclear arsenal.

A plutonium plant is typically large and generates much heat, making it easier for outsiders to detect than a uranium enrichment plant, which is more compact and can be easily hidden from satellite cameras. Centrifuges to enrich uranium can be clandestinely operated underground.

North’s atomic bombs

It’s almost impossible to independently confirm how many nuclear weapons North Korea has manufactured, based on nuclear fissile materials it has produced at Yongbyon and elsewhere.

In 2018, a top South Korean official told parliament that North Korea was estimated to have already manufactured 20-60 nuclear weapons, but some experts say the North likely has more than 100.

Estimates of how many nuclear bombs North Korea can add to its arsenal every year vary, ranging from six to as many as 18.

International diplomacy on ending North Korea’s nuclear program has stalled since 2019, when high-stakes summitry between Kim and Trump fell apart without any agreement.

At the time, Kim offered to dismantle the Yongbyon complex if he won extensive sanctions relief.

But the American side rejected his proposal, because it would be a limited denuclearization step that would leave North Korea’s other, already built nuclear weapons and nuclear facilities intact.

Kim has since shunned any diplomacy with the US and South Korea and focused on running weapons tests and perfecting nuclear missiles that target his rivals.

Since returning to office, Trump has repeatedly expressed hopes of restarting talks with Kim.

Earlier this week, Kim said he still has good memories of Trump but urged the US to drop its demand that the North surrender its nuclear arms as a precondition for resuming long-stalled diplomacy.

Analysts assess that Kim would likely perceive an enlarged nuclear arsenal as a source of greater leverage in potential talks with the US.

They say that in any potential negotiations, Kim would again seek to win sweeping sanctions relief and improved ties with the US in return for a partial surrender of his nuclear and missile programs.