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STORY: North Korea displayed images of the centrifuges that produce fuel for its nuclear bombs for the first time on Friday (September 13).

In a state TV report, leader Kim Jong Un visited the uranium enrichment facility and called for a greater production of weapons-grade material to enhance the nation's nuclear arsenal.

It's a rare look at a critical piece of the country’s nuclear program – which is banned under multiple United Nations Security Council resolutions.

The state media report did not make clear when the visit occurred nor the facility's location.

The report said Kim urged workers to produce more materials for tactical nuclear weapons, and saying the nuclear arsenal was important for self-defense against threats from the U.S. and its allies.

It also quoted Kim saying that "anti-DPRK nuclear threats" from the "U.S. imperialists-led vassal forces" have crossed a red line.

Hours later, South Korea’s unification ministry condemned the North's reveal.

“North Korea’s illegal development of nuclear weapons is a clear violation of multiple United Nations Security Council resolutions and poses a serious threat to peace on the Korean Peninsula and the world. Under no circumstances will we or the international community ever accept North Korea’s possession of nuclear weapons, and they must clearly recognize this.”

Kim highlighted the need to grow centrifuge numbers to "exponentially increase" nuclear weapons production, which may indicate that North Korea's tactical nuclear designs rely primarily on uranium.

This is significant as developing highly enriched uranium is generally less complex than plutonium.

One study suggests North Korea may have produced enough fissile material for up to 90 nuclear warheads, though about 50 are believed to be assembled.