Radiation leaks may be hobbling North Korean nuclear ambitions, new report says

SEOUL — Newly revealed evidence about radiation leaks near North Korea’s prime testing site may explain a deepening mystery — why the regime of Kim Jong-un has not conducted a new nuclear weapons test in more than five years.

A report published Tuesday contends that radioactive contamination around North Korea’s nuclear test site, buried deep under mountains in the country’s northeast, is extensive, and said the previous government in Seoul downplayed the risk in order to preserve a policy of engagement with Pyongyang.

The 80-page report, “Mapping the Risk and Effect of Radioactive Contamination of Groundwater Sources from the Punggye-ri Nuclear Test Site in North Korea,” was published by the Seoul-based civic group Transitional Justice Working Group.

TJWG has used open-source intelligence in the past to map North Korea’s mass graves. Its new report examines varied data sources to suggest there have been significant radiation leaks at Punggye-ri from past nuclear tests.

Some 900 persons who lived in that area have defected to South Korea since Pyongyang’s first nuclear test in 2006.

In 2017 and 2018, South Korean authorities, compelled by a defector activist and by public fears about Punggye-ri, conducted radiation tests on 40 escapees from the region, the report’s authors write — but “avoided publicizing issues expected to rattle North Korea.”

The report contends that the government of then-South Korean President Moon Jae-in, eager to engage with Pyongyang, was not keen to publicize the refugees’ test results. Citing data from National Assembly sources, the new report found that nine of those tested — 22.5% — exhibited “worrying levels of chromosomal abnormalities.”

“It is hard to tell if these issues are life-threatening,” acknowledged Hubert Lee, TJWG’s executive director. But he said the results were worse than those for persons exposed to the 1986 Chernobyl nuclear disaster in Ukraine.

Like many questions concerning the internal workings of the Kim regime, analyses of the nuclear program are fraught with uncertainty. North Korea watchers here are divided over why the North has not tested a nuclear device since September 2017, over why Pyongyang’s ballistic missile tests have ramped up since 2022, the role of China in restraining Pyongyang, and whether a new nuclear test is in the offing.

According to 2008 North Korean census data, 1.08 million persons live within a 40-mile radius of the Punggye-ri testing site. The report calculates that if just a quarter of the area’s public are affected by radioactive groundwater and other contamination, the victims would number around 270,000.

Moreover, the authors suggest that export and smuggling of specialized North Korean natural foods — notably its prized mountain mushrooms — may have spread contamination to China, Japan and South Korea.

Pyongyang conducted six nuclear tests between 2006 and 2017, but halted them during the period of personal diplomacy between Mr. Kim and former President Trump that failed to produce a denuclearization deal. But despite a number of shot- and long-range ballistic missile tests since then, a feared seventh nuclear test by the North has yet to occur.

“Pyongyang has concerns about the irreversible impact from the seventh nuclear test,” argued Mr. Lee. “But I also believe they want another timing: All attention now is on Ukraine, they want a dramatic moment.”

After North Korea’s most powerful-ever test, in 2017, seismic tremors were monitored by U.S. and Chinese geographic bodies, and reports were leaked from China of refugee camps being erected on the border. In 2018, the University of Science and Technology of China issued a report on a collapse deep inside Punggye-ri.

“China took a very dim view of broken window panes and cracked playgrounds in the schools of Yanji,” said analyst Christopher Green, referring to the Chinese province just north of the Korea border.

Punggye-ri lies just 60 miles from China.

Pyongyang can ill-afford to anger Beijing, which offers the isolated regime a lifeline of trade and aid, including fuel, food and medicine.

“Given the geography of the area, the line between tolerable and intolerable for China is, from Pyongyang’s perspective, uncomfortably thin,” Mr. Green, senior consultant for Korea at the International Crisis Group, added.

IEarly in 2020, satellite imagery spotted activity at Punggye-ri, suggesting a new nuclear test could be imminent. In October, South Korean President Yoon Suk Yeol’s office went into “24-hour readiness” for an anticipated detonation, but to date no test has occurred.

While both China and Russia apparently tolerate Pyongyang’s missile tests, they are warier of a new nuclear test.

“They don’t want the U.S. to use this excuse to send more assets to the region,” said Andrei Lankov, a North Korea expert at Seoul’s Kookmin University. “And they don’t want North Korea to advance its nuclear programs, as it undermines their standing as officially recognized nuclear powers.”

While some say Mr. Kim does not need more tests to cement his country’s status as a nuclear power, Mr. Lankov said North Korea’s prior tests were of strategic-yield weapons and cited constant Pyongyang references to the need for battlefield nuclear arms.

“They need to conduct another nuclear test if they want tactical nukes,” he said. “That is a new type of weapon, and they have to know it works.”