China has detained a US seismologist in connection with North Korea’s nuclear test research

China has detained a US seismologist in connection with nuclear test research as an espionage trial nears after almost two years in custody.

A Chinese-born American seismologist, who has been engaged in US-funded research aimed at detecting North Korean nuclear tests, has been detained in China for almost two years and is now facing trial on charges of espionage, as reported by his wife, US lawmakers, and two hostage advocacy organizations.

The situation involving Youlin Chen has introduced an additional layer of complexity to US-China relations as President Donald Trump aims to uphold stable connections with Beijing in the aftermath of last year’s trade conflict.

US Secretary of State Marco Rubio designated Chen, 54, as “wrongfully detained” on March 19, prioritizing his release as a key objective for the United States. Yufang Rong, his wife, stated that the Trump administration has refrained from making the designation public to allow for high-level diplomatic efforts aimed at securing his release.

A US source familiar with the case indicated that the administration was “focused on securing his release from his unjustifiable detention.”

Chen, a US citizen since 2011 residing in Boston, Massachusetts, is the sole American currently recognized as wrongfully detained in China, as reported by his wife and hostage advocacy organizations.

Rong stated that officials from the White House and State Department informed her that Trump brought up her husband’s detention with Chinese President Xi Jinping during a state visit to Beijing in May. She mentioned that Xi assured her he would investigate the issue, yet no steps have been taken since.

The US source did not provide direct confirmation that the issue was addressed. However, the source indicated that Trump and Xi share a “very good personal relationship.” This represents just one aspect of the US-China relationship. No single issue is definitive.

Rong is concerned that Chinese authorities may have already predetermined the outcome of the case.

“I believe they will convict him regardless, and the trial will take place behind closed doors,” said Rong, who is also a seismologist but does not collaborate on her husband’s work.

China dismissed allegations that Chen had been unjustly detained.

China’s judicial organs manage cases in accordance with the law, and “there is no so-called wrongful detention,” stated foreign ministry spokesperson Lin Jian.

The Foley Foundation, which monitors hostage situations, asserts that Chen is one of at least 12 Americans being wrongfully detained in China, including those who are barred from departing the country.

White House deputy press secretary Anna Kelly stated, “President Trump has stressed that he wants every American detained abroad to return home, and he has successfully reunited over 100 individuals with their families since taking office this term.”

Rong reports that Chinese officials have interrogated Chen over 100 times regarding his research on the seismic signatures associated with North Korean nuclear tests.

Eric Lebson, a former US national security official advising Chen’s family, expressed his belief that China is keen on Chen’s expertise to enhance its capability to obscure underground nuclear weapons tests through a method referred to as decoupling.

Lebson stated that Chen is employed by a US government contractor yet has never possessed a US security clearance or engaged in classified work. His research, supported by the US State Department and the Air Force Research Laboratory, was carried out in collaboration with Chinese academics utilizing publicly available Chinese data and continues to be accessible online.

A research paper published by Chen in December 2020 explored the magnitude of North Korea’s six known nuclear test explosions and the techniques used to differentiate their seismic signals from those of earthquakes. The document indicated that it was prepared for the arms control bureau of the US State Department and was “approved for public release.”

Human rights organizations contend that China’s state-secrets law permits officials to designate formerly public information as state secrets, putting researchers and others at risk of prosecution.

Chen was apprehended by Chinese state security officers at Beijing International Airport on November 5, 2024, while he was getting ready to fly back to Boston after visiting family and giving lectures at two universities.

Rong stated that her husband initially endured severe detention conditions, which included being compelled to sit on a hard stool throughout the day without the opportunity to stand, read, or exercise. She also mentioned that he was not provided with appropriate medication for diabetes and other health issues.

She mentioned that Chen has lost between 30 and 40 pounds due to poor nutrition and is still receiving insufficient medical treatment.

On May 1, 2025, Chinese authorities officially charged him with espionage. He has not yet stood trial. The case is anticipated to be highlighted during Xi’s scheduled visit to Washington in September.

US Senator Ed Markey expressed his ongoing concern for Dr. Chen’s safety and well-being.

“I hope that heightened awareness of his unjust detention will compel the Chinese government to take the appropriate action and release Dr. Chen,” Markey stated.