Earthquake research or espionage? American scientist jailed for two years in Chinese prison now faces espionage trial

A Chinese-American seismologist who conducted U.S.-funded research uncovering North Korean nuclear tests has been detained in China for nearly two years and is awaiting trial on espionage charges, Reuters reported, citing his wife, U.S. lawmakers and hostage advocacy groups.

The case of Youlin Chen, 54, has emerged as another point of tension in already strained US-China relations, even as the two countries seek to stabilize ties after last year’s trade spat.

Chen, who became a US citizen in 2011 and lives in Boston, Massachusetts, was officially labeled an “unlawful detainer” by US Secretary of State Marco Rubio. The designation, which occurred in March, elevates his release to a top US diplomatic priority. However, the Trump administration has not publicly announced the designation, reportedly to preserve space for high-level negotiations with Beijing.

According to Chen’s wife, Yufang Rong, President Donald Trump personally raised the case with Chinese President Xi Jinping during a visit to Beijing in May. She said Xi had promised to look into the matter, but there had been no progress since then.

A US official familiar with the case told Reuters that Washington remained focused on securing Chen’s release, calling his detention unjustified.

Rong fears that the Chinese authorities have already decided to convict her husband regardless of the evidence. Under Chinese law, those convicted of espionage can face severe penalties, including life imprisonment or, in particularly serious cases, the death penalty.

China has rejected claims that Chen is being wrongfully detained. Foreign Ministry spokesman Lin Jian said Chinese judicial authorities handle cases according to law and denied the existence of what he described as “so-called illegal detention.”

Considerably questioned due to nuclear testing research

According to Reuters, Chinese investigators have questioned Chen more than 100 times about his research into the seismic signatures of North Korea’s underground nuclear tests.

His wife said US embassy officials visited him several times in custody, but Chinese officials remained present during those meetings and prevented private conversations. She also said Chen was unable to see a lawyer until a year after his detention began.

Hostage advocacy groups believe that Chinese authorities may be interested in Chen’s scientific expertise. Eric Lebson, a former US national security official who advises Chen’s family, suggested that investigators may be trying to learn more about the techniques used to detect covert underground nuclear tests.

Chen’s published research examined how seismic waves generated by North Korean nuclear explosions can be distinguished from natural earthquakes. According to Reuters, the work was funded by the US State Department and the Air Force Research Laboratory, was conducted using publicly available Chinese data, and was approved for public release.

Human rights groups have argued that China’s state secrets legislation allows authorities to retroactively classify previously public information as sensitive, potentially exposing researchers to prosecution. Chen was arrested by Chinese state security officers at Beijing International Airport as he prepared to return to Boston after visiting relatives and lecturing at two universities.

His wife said his health had deteriorated significantly in custody. She claimed he initially faced harsh treatment, was denied adequate medication for diabetes and other medical conditions, and has since lost 30 to 40 pounds due to poor nutrition.

He was formally charged with espionage in May 2025, but has yet to stand trial. Reuters reported that his case is expected to remain an important issue in ongoing diplomatic negotiations between Washington and Beijing.