U.N. Nuclear Watchdog Warns North Korean Reactor 'Has Reached Criticality' After ICBM Launch

The International Atomic Energy Agency (IAEA), the U.N.’s nuclear watchdog, warned on Thursday that it had evidence that North Korea is operating a new reactor at its Yongbyon nuclear complex, potentially generating fuel used to create nuclear warheads.

The warning, from IAEA chief Rafael Grossi, follows belligerent statements from communist dictator Kim Jong-un in which he stated his country was ready to use nuclear weapons to attack America if it makes a “wrong decision.” Kim made the remarks, according to North Korea’s state propaganda outlets, following the testing of a solid-fuel intercontinental ballistic missile (ICBM), the “Hwasong-18,” on Monday.

North Korea has for decades operated an illegal nuclear weapons program, insisting the development is necessary to prevent America from toppling the repressive communist regime. North Korea has technically been at war with America, and South Korea, since 1950, though active hostilities in the Korean War ended with an armistice agreement in 1953. As a formal ally in that war with North Korea, China is also a party to the war. Beijing warmly welcomed a top North Korean diplomat to reiterate its support for the regime on Monday, the day of the ICBM launch.

Grossi said in a formal statement published Thursday that the IAEA had “observed increased levels of activity at, and near, the Light Water Reactor (LWR) at Yongbyon, and also – since mid-October – a strong water outflow from its cooling system.” Emphasizing the fact that North Korea has not allowed the IAEA to regularly inspect its nuclear sites since 2009, Grossi said the IAEA could not fully confirm the activity, but its monitoring systems had sufficient reason to believe that the reactor was operative.

“More recent observations indicate that this water discharge is warm, which is also consistent with ongoing commissioning of the LWR, a process that takes some time for any new reactor,” Grossi said. “However, the discharge of warm water is indicative the reactor has reached criticality.”

Grossi noted that the reactor “can produce plutonium … so this is a cause for concern.” Plutonium is a radioactive element that can be used to develop nuclear weapons.

“It remains the case that without access to the facility the Agency cannot confirm its operational status,” he added, describing the continued existence of North Korea’s nuclear weapons program as illegal under international law and “deeply regrettable.” He concluded by urging North Korea to abide by international law and cooperate with the IAEA, including allowing the agency to aid in maintaining the safety of the Yongbyon facility.

The news agency Reuters cited a second source, the James Martin Center for Nonproliferation Studies (CNS) in California, whose study of satellite images of North Korea similarly concluded that Yongbyon’s nuclear reactor was online and could be “a significant source of nuclear material.” Reuters noted that a separate study by the Institute for Science and International Security estimated that the Kim regime owned between 31 to 96 nuclear warheads. It remains unclear if the Hwasong-18 is compatible with all of them.

The Hwasong-18 is the newest ICBM model North Korea has publicly claimed to possess. Unlike its predecessors, it is believed to be a solid-fuel missile model, which allows North Korea to prepare it for firing at a much faster speed than previous liquid-fuel missiles.

“Compared to the liquid ICBMs, the solid-propellant HS-18 will be easier and safer to operate in the field; it will need fewer support vehicles, and so should be easier to conceal (and thus somewhat safer from attack),” the North Korea monitor site 38 North reported on Thursday, “and it has the potential to be more reliable. But Gulf War experience indicates that camouflaged liquid ICBMs are likely to be highly survivable in the field, and North Korea has some 35 years’ experience in field deployments of liquid missiles.”

North Korea fired what it claimed to be a Hwasong-18 into the East Sea (or Sea of Japan) on Monday. The regime’s Korean Central News Agency (KCNA) announced the launch in an extensive article on Wednesday claiming that Kim Jong-un personally presided over the missile launch and intended it to be a threat to America and South Korea in the face of increased military cooperation between the two countries. Kim was reportedly particularly incensed by the creation of the Nuclear Consultative Group agreed upon by South Korean President Yoon Suk-yeol and American President Joe Biden in July, intended to give South Korea more information and input in the deployment of American nuclear-capable assets to the country.

“The present situation clearly shows the inveterate confrontation stand of the U.S. and its predominant stooges keen on their unchangeable instinctive and constitutional ambition for aggression,” KCNA thundered in commentary on Wednesday, “and predicts a black augury of total destruction of the security environment in the Korean peninsula to be further aggravated.”

Summarizing Kim’s statements at the ICBM launch, KCNA claimed that Kim described the launch as “an occasion to clearly show what action the DPRK has been prepared and what option the DPRK would take when Washington makes a wrong decision against it,” indicating Kim was ready to use nuclear weapons against America if he deemed it necessary.

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