SEOUL, South Korea — North Korea continues to upgrade its nuclear facilities, the head of the U.N.’s atomic agency said Wednesday in Seoul.
His visit came in the midst of a Middle East conflict in which Iran — which has not acquired nuclear capabilities — has suffered punishing Israeli and U.S. airstrikes.
“We have been able to confirm that there is a rapid increase in the operation of the Yongbyon reactor … and the activation of other facilities apart from Yongbyon,” Rafael Mariano Grossi, director-general of the International Atomic Energy Agency, said in Seoul in televised remarks. “All of them point to a very serious increase in the capability of [North Korea] in the area of nuclear weapons production, which is estimated at a few dozen warheads.”
The Yongbyon complex, in northwestern North Korea, has generated spent plutonium as a fissile material, but North Korea is also enriching uranium, considered more effective for weaponization.
Earlier, Mr. Grossi had told IAEA governors that the agency was monitoring a new building at Yongbyon similar to a uranium-enrichment facility at Kangson, near the capital Pyongyang, Reuters reported.
Yongbyon is built around a plutonium-based reactor acquired from the Soviet Union. It started operations in 1986.
In 1994, the “Agreed Framework,” a multilateral effort to halt plutonium production at Yongbyon in exchange for the provision of a less weaponizable light-water reactor, was reached.
Spent fuel from plutonium can be processed into nuclear arms, and production was frozen, but the deal suffered from mistrust on both sides.
In 2002, U.S. officials accused North Korea of operating a separate, secret, uranium-enrichment facility. That accusation led to the unraveling of the Agreed Framework in 2003. That year, Pyongyang exited the Nuclear Non-Proliferation Treaty, or NPT.
In 2006, it tested its first nuclear device and would detonate five more, with increasing yields, through 2017. It also showed off its long-suspected uranium-enrichment facilities in 2010.
Questions still hang over whether North Korea has mastered the technology to secure the reentry vehicles that tip ballistic missiles when they reenter the Earth’s atmosphere and whether the state has successfully compressed its fissile materials down to warhead size.
Regardless, it is widely accepted — though not formally recognized — that North Korea is a nuclear state.
North Korea’s expanding nuclear capabilities could undermine arguments against proliferation, given that nations that have surrendered nuclear arms — Ukraine — or have abandoned nuclear programs — Iraq and Libya — have suffered devastating conventional attacks.
On March 5, seven days into the Iran conflict, that point was underscored in a press conference by Israel’s plain-speaking envoy to South Korea.
“Our goal is that Iran won’t have nuclear weapons,” said Israeli Ambassador to South Korea Rafael Harpaz. “We will do our utmost to avoid Iran from becoming North Korea.”
He is not alone in his belief. Five days later, American geopolitical thinker Francis Fukuyama endorsed an X post stating, “North Korea was right about nuclear weapons.”
The number of warheads North Korea possesses is unknown; consensus estimates are around 50.
Per the Stockholm International Peace Research Institute in 2025, Russia deployed 5,580; the U.S., 5,328; and China, 500.
How many North Korea plans to build is unknown, but state leader Kim Jong-un regularly urges upgrades to nuclear arms, known colloquially as North Korea’s “sacred sword” and constitutionally enshrined.
“It is our party’s firm will to further expand and strengthen our national nuclear power, and thoroughly exercise our status as a nuclear state,” he said, per state media at the conclusion of the 9th Party Congress in February. “We will focus on projects to increase the number of nuclear weapons and expand nuclear operational means.”
Delivery systems encompass large-caliber multiple-launch rocket systems, cruise missiles and ballistic missiles.
Three seaborne platforms — an unmanned nuclear torpedo, and submarine- and destroyer-launch systems — are at various stages of development.
The country’s “sacred sword” was forged at massive cost. North Korea is believed to spend — at a conservative estimate — 26% of GDP on defense.
“We think of lower and upper bounds of how many warheads they have, and the next question is what is the marginal utility of an additional warhead or warheads,” said Daniel Pinkston, a Seoul-based international relations expert. “There is opportunity cost: You have food insecurity, but you have nuclear weapons, and engineers and scientists working on this, and these skills are not easily transferred into agricultural production.”
It is not simply external threats that motivate Pyongyang: Internal dynamics exist.
U.S. attacks on Iran have been described by state media as “gangster-like conduct.”
America is widely demonized in North Korea — from actors wearing rat tails playing U.S. troops in kindergarten plays to bloody artworks illustrating alleged U.S. atrocities during the 1950-53 Korean War.
“Authoritarian regimes generally exaggerate external threats, so they can use fear to control and manage society: ‘The Yankees are going to invade any day now,’” said Mr. Pinkston. “There is a rally-round-the-flag effect — the same in the U.S. as the ‘Teflon Effect’ — that deflects criticism, but they have been doing it for 70 years.”
