China Detains US Seismologist Who Studied North Korean Nuclear Tests

Jul 13, 2026

American seismologist Youlin Chen has been detained in China for nearly two years on spying charges related to his US-funded research on detecting North Korean nuclear tests. The US State Department has designated Chen as 'wrongfully detained,' and President Trump has reportedly raised the case with Xi Jinping. Advocates fear China seeks his expertise to conceal its own nuclear tests, while his wife reports he has endured harsh conditions and significant weight loss.

Chen espionage charges

▪Youlin Chen, a Chinese-born American seismologist, has been detained in China for nearly two years on spying charges.
▪Chen's wife, Yufang Rong, believes he will be convicted regardless of the evidence in a trial held behind closed doors.
▪He was formally charged with espionage on May 1, 2025, but has not yet stood trial.
▪Chen was arrested by Chinese state security officers on November 5, 2024, at Beijing International Airport.

Nuclear test detection research

▪Under its state-secrets law, China can retroactively classify public data as national security secrets.
▪Chinese officials have interrogated Chen more than 100 times about his research on North Korean nuclear tests.
▪Advocate Eric Lebson believes China wants to use Chen's expertise to improve its ability to conceal underground nuclear tests via a technique called 'decoupling'.
▪His work was unclassified, used publicly available Chinese data, and was conducted in collaboration with Chinese academics.
▪Chen's research focused on detecting North Korean nuclear tests and was funded by the US State Department and the Air Force Research Laboratory.

US-China diplomatic efforts

▪President Donald Trump reportedly raised Chen's detention with Chinese leader Xi Jinping during a state visit to Beijing in May.
▪The Trump administration has withheld a public announcement about the case to allow for high-level diplomacy.
▪US Senator Ed Markey expressed hope that increased attention will pressure the Chinese government to release Chen.

Detention conditions

▪At the start of his detention, Chen was forced to sit on a hard stool all day and was denied exercise or reading materials.
▪Chen has lost 30 to 40 pounds (13.6 to 18.1 kg) and receives insufficient food and poor-quality medication for his diabetes.
▪A Chinese lawyer was only allowed to see Chen after he had been detained for more than 13 months.

Wrongful detention designation

▪Chen, who became a US citizen in 2011, is the only American currently held in China designated as wrongfully detained.
▪On March 19, US Secretary of State Marco Rubio designated Youlin Chen as 'wrongfully detained,' making his release a top US priority.
▪The Foley Foundation, a hostage advocacy group, believes at least 12 Americans are unjustly held in China, including those under exit bans.