As Kim Jong-un extends one hand, he beckons with the other for nuclear development

[A STUDY OF KIM JONG-UN 8]

When North Korean leader Kim Jong-un met then-President Moon Jae-in's special delegation in Pyongyang on March 5, 2018, he offered what sounded like a promise.

"I heard that you lost sleep early in the morning attending NSC meetings because of us; it must now be a habit to wake up early,” Kim said to Moon. “I will ensure that the president does not lose sleep early in the morning.”

At the time, North Korea regularly launched missiles late at night and before dawn. Kim followed those remarks with a series of moves that suggested he intended to keep that promise.

On April 20, 2018, just a week before his summit with Moon at Panmunjom, the inter-Korean truce village at the demilitarized zone, Kim convened a plenary meeting of the North's ruling Workers' Party and announced that North Korea would suspend nuclear tests and intercontinental ballistic missile (ICBM) launches.

On May 24, 2018, about three weeks before Kim’s first summit with U.S. President Donald Trump, North Korea invited journalists from South Korea, the United States, China, Russia and Britain to witness the demolition of tunnels at the Punggye-ri nuclear test site in Kilju County, North Hamgyong Province, where the North had conducted six nuclear tests.

Questions immediately emerged.

"We asked how deep the tunnels were, but received no answer," members of the South Korean press pool said after returning home. “A Korean Central News Agency [KCNA] reporter said North Korea had destroyed eight locations, but we could not verify that from the sounds of the explosions. When we asked again, the reporter avoided the question."

North Korean officials showed foreign reporters dynamite and wiring installed inside the tunnel entrance before the demolition. Afterward, however, they prevented journalists from returning to the site to inspect the damage.

When one reporter expressed skepticism, an official from a North Korean nuclear weapons institute offered reassurance.

"The blast came from deep inside. If only the entrance had exploded, you would not have seen that kind of effect," the official said at the site.

Another moment left reporters unconvinced.

As journalists crossed a stream near Tunnel No. 3, a KCNA reporter urged a South Korean reporter to drink the water and insisted that no radioactive contamination existed. When the South Korean reporter replied that the KNCA reporter should drink it first, they declined.

If North Korea had truly destroyed the tunnels, the episode might have ended as little more than an odd memory from a rare visit to the secretive site. Instead, it took on new meaning years later.

The return of Tunnel No. 3

Satellite imagery and intelligence assessments indicated that North Korea began restoring Tunnel No. 3 around March 2022. By June that year, South Korean intelligence agencies reportedly concluded that the tunnel had regained sufficient functionality to support a seventh nuclear test.

The speed of the restoration strengthened suspicions that North Korea had destroyed only the entrance rather than the entire tunnel system.

The restoration effort pointed to a larger possibility. Even as North Korea pursued diplomacy in 2018, Kim may have continued laying the groundwork for the country's next phase of nuclear and missile development.

Kim's own words offer some clues. 

A decade of Kim's words

The JoongAng Ilbo partnered with SpeechLog, an AI-based big data analysis firm, to examine 137,513 Rodong Sinmun articles and more than 18 million entries published between January 2016 and January this year.

The analysis focused on Kim's public remarks during a decade that included nuclear advances, summit diplomacy, the collapse of negotiations and North Korea's growing partnership with Russia.

Researchers divided the period into four phases.

The first phase covered 2016 and 2017, when North Korea accelerated its nuclear and missile programs and conducted a series of weapons tests.

The second spanned 2018 through February 2019, when summit diplomacy among North Korea, South Korea and the United States reached its peak, including meetings between Kim, President Moon and President Trump.

The third covered February 2019 through 2022, after the Hanoi summit between Kim and Trump ended without an agreement and during the Covid-19 pandemic, when North Korea largely shut its borders and diplomatic engagement stalled.

The fourth covered 2023 through January this year, when North Korea and Russia expanded military cooperation as the war in Ukraine reshaped regional security dynamics and Pyongyang emerged as a more important strategic partner for Moscow.

Military talk as usual

An analysis of Kim's remarks by topic found that in the first phase, military-related language accounted for about 10 percent of Kim's remarks, but decreased during the summit diplomacy of 2018 and early 2019, falling to 5.2 percent.

That pattern continued after the Hanoi summit. Even after the summit between Kim and Trump ended without an agreement, military-related references remained at roughly the same level, accounting for about 5 percent of Kim's remarks during the third phase and 4.5 percent during the fourth.

Kim turned to diplomacy after declaring the completion of North Korea's nuclear force in November 2017. The first phase thus represented an unusual period in which he focused heavily on advancing the country's nuclear and missile capabilities to strengthen his leverage ahead of negotiations.

After the first phase, the share of military-related remarks fell by about half and remained largely unchanged for nearly a decade. 

New weapons during diplomacy

The analysis also found signs that North Korea continued developing more advanced nuclear weapons even during the years of summit diplomacy.

References specifically tied to nuclear deterrence, including terms such as "nuclear" and "self-defense rights," registered at 0.101 percent during the second phase, fell briefly to 0.047 percent in the third phase and then rose to 0.085 percent during the fourth phase.

In other words, Kim discussed nuclear capabilities more frequently during the years of summit diplomacy than during other periods.

Kim smiled for the cameras during the diplomatic opening, but references to nuclear weapons remained a constant theme in his public remarks. Intelligence assessments from 2018 pointed in the same direction.

In November 2018, South Korea's National Intelligence Service told lawmakers that North Korea likely continued efforts to make its nuclear warheads smaller and lighter even after the Singapore summit between Kim and Trump.

A 2020 report by the United Nations Security Council's Panel of Experts also raised the possibility that North Korea added as many as 15 nuclear warheads after the summit began.

Even as Kim met with Moon in Pyongyang and later held talks with Trump, there is little evidence that North Korea put its nuclear weapons program on hold.

The Hanoi summit may have ended without the outcome Kim wanted, but he had already signaled another course of action before the meeting took place.

In his New Year's address on Jan. 1, 2019, Kim offered a warning.

“If the United States does not keep the promise it made in the eyes of the world, and out of miscalculation of our people’s patience, it attempts to unilaterally enforce something upon us and persists in imposing sanctions and pressure against our Republic, we may be compelled to find a new way for defending the sovereignty of the country and the supreme interests of the state and for achieving peace and stability of the Korean peninsula,” Kim said.

That "new way" became visible about three years later.

In 2022 alone, Pyongyang carried out dozens of missile launches as it worked to build a wider range of missiles capable of carrying nuclear weapons. According to the South’s Joint Chiefs of Staff, North Korea launched ballistic missiles 34 times in 2022, the highest annual total on record.

The North also conducted another 21 ballistic missile launches in 2023. Many of the systems unveiled from 2022 to 2023 require years of development. Their appearance suggests that North Korea continued weapons research even during the years that observers viewed as a period of peace.

The most striking example may have been the Hwasong-17 ICBM, which North Korea first unveiled during a military parade marking the 75th anniversary of the Workers' Party on Oct. 10, 2020.

Analysts estimated its length at 22 to 24 meters (72 to 78 feet), making it one of the largest road-mobile ICBMs in the world, longer than the U.S. Minuteman III at 18.2 meters, China's DF-41 at about 21 meters and Russia's Topol-M at 22.7 meters.

North Korea launched the Hwasong-17 three times in 2022 and touted improvements in its performance. Experts estimate that developing a missile of that scale, including securing sufficient engine thrust and increasing payload capacity, would require at least three to four years.

The estimated development timeline suggests that Pyongyang began work on the massive ICBM during the period of summit diplomacy with Seoul and Washington.

Observers first detected signs of the Hwasong-17 development program in December 2019, when North Korea conducted a test of a new ICBM engine at the Sohae Satellite Launching Station in Cholsan County, North Pyongan Province. By then, only about 10 months had passed since the Hanoi summit between Kim and Trump ended without an agreement, yet the program already appeared well advanced.

The Hwasong-8 hypersonic missile tells a similar story. Kim revealed the project at the Eighth Party Congress in January 2021 and said engineers had completed its design. Later that year, on Sept. 28, North Korea launched a missile equipped with a hypersonic glide vehicle and claimed success.

Pyongyang followed with two more hypersonic missile launches in January 2022. State media said the missile reached speeds of up to Mach 10, glided through the atmosphere, made a sharp turn in flight and struck a target 1,000 kilometers (621 miles) away.

With experts generally estimating that countries need at least four to six years to develop a hypersonic missile, the timeline suggests that the North began work on the program around 2017.

The KN-23 short-range ballistic missile provides an even clearer illustration of Kim’s intentions.

North Korea launched the KN-23 on May 4 and May 9, 2019, just three months after the Hanoi summit. Developing what the regime then called a "new tactical guided weapon" in only three months was virtually impossible.

Even as a series of summits between North Korea, South Korea and the United States raised hopes for peace on the Korean Peninsula, Kim slowed missile testing but continued weapons development.

 The scientist behind the program

North Korea's nuclear efforts depended on a small group of scientists who helped drive its development.

Hong Sung-mu, the former deputy director of the North's ruling Workers' Party's Munitions Industry Department, has played a central role in the country's nuclear weapons program since the era of Kim Jong-il.

Hong’s name first appeared in public in September 2010, when delegates elected him an alternate member of the Central Committee of the Workers’ Party at the Third Party Conference, shortly after North Korea named Kim Jong-un as his father’s successor.

Despite Hong’s prominence, little information about him exists in public records. The South Korean Ministry of Unification’s information portal on the North does not even list his year of birth.

Yet behind the scenes, Hong remained at the center of Pyongyang's nuclear development effort.

Information obtained by the JoongAng Ilbo from multiple sources indicates that Hong was born in 1942 and studied in the Soviet Union.

After specializing in nuclear science there, he returned to North Korea and spent many years as a researcher at the Second Academy of Natural Sciences, the country's leading weapons research institution.

He later served as vice president and then president of the academy before moving to the Workers' Party's Munitions Industry Department, which oversees North Korea's defense industry and its nuclear and missile programs. His role earned him the nickname of "chief nuclear engineer."

Hong rose further after Kim Jong-un took power. At the Seventh Party Congress in May 2016, the first party congress under Kim, officials promoted him to full membership on the Central Committee.

He also accompanied Kim on numerous inspections related to nuclear development following North Korea's fifth nuclear test in September 2016.

In 2017, the year Kim declared the completion of North Korea's nuclear force, Hong became first vice director of the Munitions Industry Department.

His standing became even clearer after the country conducted a sixth nuclear test in September 2017. He attended a celebratory banquet wearing the insignia of a four-star general, signaling Kim's trust in him and his status as one of the key figures behind the country's weapons programs.

Other officials involved in missile development, including Hong Yong-chil, a deputy director of the Workers' Party's Machine-Building Industry Department, and Jang Chang-ha, chief of the country's missile bureau, received three-star ranks. The move pointed to Hong’s standing within the hierarchy.

The scientist appeared again at a military parade marking the 75th anniversary of the founding of the Korean People's Army in February 2023, wearing four Hero of the Republic medals on his chest.

North Korea's nuclear elite

Kim’s support for scientists helped drive Hong’s rise. Observers have also noted that young North Koreans increasingly favor careers in science and technology.

Multiple defectors have said that the North identifies talented children at a young age, channels them into weapons programs and tightly controls their lives. They face long-term exposure to radiation risks and often have little freedom in personal matters, including marriage.

Between 2023 and 2025, researchers at the National Radiation Emergency Medical Center in South Korea examined 174 North Korean defectors who had lived near the Punggye-ri nuclear test site in Kilju County, North Hamgyong Province, after North Korea's first nuclear test in October 2006. They found possible genetic damage linked to radiation exposure in 44 people, or 25 percent of those tested, according to Seoul's Unification Ministry.

Experts say nuclear scientists likely faced even greater exposure.

Despite those risks, scientific careers remain one of the few paths to upward mobility in North Korea's rigid social system.

One senior South Korean official recalled a conversation from a 2018 visit to Pyongyang as part of the inter-Korean summit delegation. The official asked a high school senior on Changgwang Street about their future plans.

"I want to attend Kim Il Sung University and become a researcher," the student replied, according to the official.

For North Koreans from ordinary backgrounds, Hong represents the pinnacle of what some defectors call North Korea's "nuclear ladder." Many young aspiring scientists regard him as a role model, according to defectors.

Hong enjoyed the trust of the Kim family long before Kim Jong-un came to power. The leader's father reportedly allowed him to live not on Changgwang Street, the residential district reserved for senior officials, but inside the Workers' Party's complex, where Kim maintained one of his residences.

Some analysts believe Hong stepped back from frontline duties after the Ninth Party Congress in February, when North Korea replaced many officials in their 70s and older. His name did not appear on the lists of Central Committee members and alternate members, a key indicator of political standing.

Even so, most experts expect him to remain influential. Given the trust the Kim family apparently has in him, they believe he will continue advising the leadership and supporting efforts to advance North Korea's nuclear and missile programs.

BY YOO JEE-HYE , CHUNG YEONG-GYO AND SHIM SEOK-YONG [[email protected]]