A Chinese-born American seismologist who conducted U.S.-funded research on detecting North Korean nuclear tests has been held in China for nearly two years and is awaiting trial on espionage charges, according to his wife, U.S. lawmakers and two hostage advocacy organizations.
The case of Youlin Chen, reported for the first time, adds another strain to relations between the two nuclear-armed powers as President Donald Trump seeks to stabilize ties with Beijing after last year’s trade tensions.
Secretary of State Marco Rubio on March 19 designated Chen, 54, as “wrongfully detained,” making his release a top U.S. priority. The Trump administration has withheld a public announcement to allow space for high-level diplomacy aimed at securing his freedom, according to his wife, Yufang Rong.
A U.S. source familiar with Chen’s case said the administration was “focused on gaining his release from his unjustifiable detention.” The source spoke on condition of anonymity to discuss sensitive diplomatic talks.
Youlin Chen, a U.S. citizen living in Boston, is the only American currently designated as wrongfully detained in China, according to his wife and hostage advocates.
His wife said the White House and State Department told her that President Donald Trump raised Chen’s case with Chinese President Xi Jinping during a May visit to Beijing, though no action has followed. A U.S. official confirmed the leaders maintain close ties but said no single issue defines the broader relationship.
Chen’s wife fears Beijing has already judged him guilty before trial, with espionage charges in China carrying penalties of up to life imprisonment or, in severe cases, the death penalty. The Foley Foundation says Chen is among at least 12 Americans it believes are being unjustly held by China.
Interrogated About Nuclear Test Studies
U.S. officials have visited Chen several times, but Chinese officials were present during meetings, limiting private communication, his wife said. His lawyer was allowed access only after more than 13 months in detention.
Chen was questioned over 100 times about his research on seismic signals from North Korean nuclear tests. A hostage advocacy group suggested China may want to use his expertise to improve methods for hiding underground nuclear tests, including “decoupling” techniques.
Chen, who worked for a U.S. government contractor, never held a security clearance or handled classified material. His research, funded by the U.S. State Department and Air Force Research Laboratory, relied on publicly available data and examined seismic patterns from North Korea’s nuclear tests.
Human rights groups say China’s broad state-secrets laws allow authorities to later classify previously public information as sensitive, potentially putting researchers at risk.
Arrested Before Returning To Boston
Chen was arrested by Chinese state security officers on November 5, 2024, at Beijing International Airport while preparing to return to Boston after visiting family and giving university lectures, according to his wife and a hostage advocate.
His wife said Chen initially endured harsh detention conditions, including being forced to sit on a stool for long periods and being denied access to needed medication. She said he has since lost 30 to 40 pounds and receives inadequate food and medical care.
Chen was formally charged with espionage on May 1, 2025, but has not yet faced trial. U.S. Senator Ed Markey has called for his release, expressing concern over his safety and detention.
(With inputs from Reuters)
