China detains US nuclear expert on spying charge, his family says

China has detained a US seismologist who has been monitoring nuclear tests for nearly two years on espionage charges, his family said.

Chen Youlin, 54, was arrested in November 2024 during a trip to Beijing to visit family, according to hostage advocacy group Global Reach. The family decided to speak out when they saw no sign that Beijing had released Chen.

Her husband, Rong Yufang, also a seismologist, said Chen worked closely with Chinese colleagues and that the allegations were “both false and contrary to the public and collaborative nature of his work.”

His published work focuses on North Korea, a close friend of China that has long been sanctioned for its nuclear weapons program and underground testing.

It is unclear whether and how Chen’s work affected Beijing’s nuclear program. US intelligence suggests China is developing a new arsenal and conducting secret tests, which Beijing denies.

When asked about the case at its daily press briefing on Tuesday, China’s foreign ministry said “judicial authorities are handling cases in accordance with the law.”

“There is no such thing as so-called unjust detention,” said ministry spokesman Lin Jian. In China, espionage convictions can result in life imprisonment or death.

Chen is currently the only US citizen identified as “wrongfully detained”.

“I have not been able to talk to my husband for more than 600 days, and I am concerned for his health and well-being,” Rong said in a statement via Global Reach. he said.

In an interview with Reuters, she said Chinese authorities questioned her husband more than 100 times about his work and was not allowed to see a lawyer during the first 13 months of his detention.

Born in China, Chen became a US citizen in 2011. He lives in Boston, Massachusetts.

He specialized in using seismological data to determine nuclear testing and undertook many projects funded by the US government. Rong said his work with colleagues in China was always done in a “transparent” manner.

“It is achieving exactly the kind of people-to-people interaction that the Chinese government says it wants,” he added.

Chen’s work included a study in December 2020 examining seismic data recorded across Asia, including China, to improve nuclear test monitoring and yield prediction methods.

According to Global Reach, “There are suspicions within the U.S. government that Chen’s arrest was spurred by China’s conduct of nuclear tests in violation of the Comprehensive Nuclear Test Ban Treaty.”

The group said Chen’s expertise would give China “the opportunity to learn as much as possible about US seismic detection methodologies so they can create countermeasures that will allow them to circumvent the agreement.”

The treaty aims to ban all nuclear explosion tests on Earth, but some “nuclear-capable” states have yet to ratify it. These include the United States and China, which have imposed a voluntary moratorium on explosive nuclear tests.

In June 2020, during Donald Trump’s first presidency, his administration accused Beijing of conducting a secret underground nuclear test at the Lop Nur facility in the northwest of the country. China has rejected the allegations as unfounded and politically motivated.

The Foley Foundation, another US-based hostage advocacy group, said Chen’s health was concerning, noting that Chen suffered from diabetes, high blood pressure and high cholesterol.

“He needs reliable access to treatment and care that were not available at the time of his wrongful incarceration,” the group said.

U.S. Senator Edward Markey, a Massachusetts Democrat, said Beijing’s “treatment of Chen [its] partnership [with the US] and may deter other academics from interacting with their colleagues in China.”

“Hopefully, the growing attention to his unjust detention will compel the Chinese government to do the right thing and release Chen,” he said in a statement released Tuesday.

Details of Chen’s detention come a month after China confirmed it had detained another US academic, Min Zin, the director of a Myanmar-focused think tank.

Beijing accused Min Zin of spying and endangering Chinese national security.