Youlin Chen, a 54-year-old Chinese-born American seismologist, has been detained in China on espionage charges since November 5, 2024, during a trip to Beijing to visit family [1, 2]. Chen, who became a US citizen in 2011 and lives in Boston, Massachusetts, specializes in seismological detection of nuclear tests, particularly those by North Korea, and has published research funded by the US government [1, 3, 4, 2, 5].

Chen has been interrogated more than 100 times and was denied access to a lawyer for the first 13 months of his detention, according to available reports [1]. His wife, Rong Yufang, also a seismologist, has not spoken with him for over 600 days and has expressed grave concern for his health, pointing out that Chen suffers from diabetes, high blood pressure, and high cholesterol [1, 2, 5]. Rong has stated, "Youlin has never held a US government security clearance and to suggest he was involved in espionage is both wrong and inconsistent with the public and collaborative nature of the work that he has done" [2].

The US government designated Chen as "wrongfully detained" on March 19, 2026, with Secretary of State Marco Rubio naming his release a top priority [3, 4, 5]. In May 2026, President Donald Trump raised Chen's detention directly with Chinese leader Xi Jinping during a state visit to Beijing, during which Xi reportedly pledged to look into the case [3, 2, 5]. Despite this commitment, reports as of July 2026 indicate no progress toward Chen's release [2].

China rejects US allegations of wrongful detention. A spokesman for China’s foreign ministry, Lin Jian, said, "There is no such thing as so-called wrongful detention" and emphasized that espionage cases are handled by judicial authorities under Chinese law, with penalties ranging up to life imprisonment or death [1, 5].

Chen remains the only US citizen currently designated as wrongfully detained by the US government in China. His detention is believed to be linked to US accusations that China violated the Comprehensive Nuclear Test Ban Treaty with underground nuclear tests and fears that Chen's expertise could expose US detection methods, though these links are less certain [1, 2].

The US has withheld public announcement of Chen’s detention initially to allow for diplomatic negotiations. As of August 2026, Chen has been held for nearly two years, and his family and government officials continue to press for his release.