A Chinese-born American seismologist, Youlin Chen, has been held in China for nearly two years and now faces trial on espionage charges, according to his wife, US lawmakers and hostage advocacy groups. Chen, 54, was arrested at Beijing Capital International Airport on 5 November 2024 as he prepared to return to Boston after delivering lectures at Chinese universities. His US-funded research focused on distinguishing seismic signatures of North Korean underground nuclear tests from natural earthquakes, work conducted with publicly available Chinese data and published in open-access journals. In March 2026, US Secretary of State Marco Rubio designated Chen as “wrongfully detained,” making his release a top diplomatic priority, though the Trump administration withheld a public announcement to preserve space for high-level negotiations.

Viewed from Washington, the detention is unjustified and part of a pattern of arbitrary legal action against foreign researchers. US officials, speaking on condition of anonymity, described the case as a key irritant in bilateral relations. President Donald Trump personally raised the matter with Chinese President Xi Jinping during a state visit to Beijing in May 2026, and Xi promised to look into it, but no progress has been reported. Chen’s wife, Yufang Rong, said her husband never held a US security clearance and that the espionage allegation contradicts the open, collaborative nature of his work. Hostage advocacy groups, including the Foley Foundation and Global Reach, argue that China’s broad state-secrets legislation allows authorities to retroactively classify previously public information, exposing scientists to prosecution. They also suggest Beijing may be seeking to extract expertise on concealing underground nuclear tests through a technique known as decoupling.

Beijing rejects the wrongful detention designation outright. Foreign Ministry spokesperson Lin Jian stated that Chinese judicial authorities handle cases according to law and that “there is no instance of wrongful detention.” Chinese investigators have interrogated Chen more than 100 times about his seismic research, and he was denied access to a lawyer for over 13 months, according to his wife. US consular officials have visited him, but always with Chinese personnel present, preventing private conversation. Rong alleges her husband’s health has deteriorated sharply, with inadequate medication for diabetes and a weight loss of 30 to 40 pounds due to poor nutrition and harsh initial conditions.

The case unfolds amid a broader context of mutual espionage accusations and diplomatic incidents, including the 2023 Chinese balloon episode and the recent detention of US scholar Min Zin on similar charges. At least 12 Americans are currently considered unjustly held in China, according to advocacy groups. From Beijing’s perspective, the prosecution is a sovereign legal matter, and external pressure is interference in internal affairs. No trial date has been set, and Rong expects proceedings to be held behind closed doors. The dossier is expected to feature in further diplomatic engagements, including a possible meeting between Trump and Xi in Washington in September, but for now the case remains unresolved, deepening the trust deficit between the two nuclear-armed powers.