China detains US seismologist who has studied North Korean nuclear tests
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- Youlin Chen, a 54-year-old Chinese-born American seismologist, has been detained in China for nearly two years and charged with espionage — a crime that can carry life imprisonment or the death penalty, according to his wife Yufang Rong and two hostage advocacy groups.
- Secretary of State Marco Rubio designated Chen as "wrongfully detained" on March 19, making his release a top US priority, though the Trump administration withheld a public announcement to preserve diplomatic space, a US source told Reuters.
- Chen was arrested on Nov. 5, 2024, at Beijing International Airport while returning to Boston after lecturing at two Chinese universities, and has since been interrogated more than 100 times about his work on seismic signatures of North Korean nuclear tests, Rong said.
- President Trump raised Chen's detention with Xi Jinping during a May state visit to Beijing, where Xi promised to look into it; Rong said Beijing has taken no action, and the case is expected to resurface during Xi's planned September visit to Washington.
- Chen's research was funded by the State Department's arms control bureau and the Air Force Research Laboratory, was conducted with Chinese academics using publicly available data, and was approved for public release — he has never held a US security clearance, according to former national security official Eric Lebson.
- Lebson's advocacy group believes China wants to extract Chen's expertise to improve its ability to conceal underground nuclear tests through a technique called decoupling — the same method the US accused Beijing of using to mask a low-yield test on June 22, 2020.
- Rong said Chen has lost 13 to 18 kilograms in detention, is given insufficient protein and poor-quality medications for his diabetes, and fears a closed-door trial: "I believe they will convict him no matter what."
Why it matters: Chen is the only American currently in China designated wrongfully detained, and his case sits at the intersection of two US-China flashpoints: hostage diplomacy and the nuclear testing dispute. His advocates assess Beijing wants his open-source seismic expertise to refine decoupling — the same technique the Trump administration accused China of using to hide a June 2020 test — giving the case strategic weight well beyond a single imprisonment.
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