Who is Chen Youlin? US scientist who tracked North Korea nuclear tests detained in China

A Chinese-born American seismologist who published US-funded work on tracking nuclear tests has reportedly been detained in China for nearly two years on espionage charges.

54-year-old Chen Youlin was arrested in November 2024 during a family visit to Beijing. His wife Rong Yufang, also a seismologist, worked closely with Chinese colleagues, and that the allegations are both incorrect and conflict with the collaborative, public nature of his work.

At present, it is unclear if and how Chen’s work mentioned Beijing's nuclear programme. According to US intelligence, China is building a new arsenal and has conducted secret tests, allegations which Beijing denies.

In this connection, the ministry's spokesman Lin Jian said: “There is no such thing as so-called wrongful detention.”

“I have not been able to speak with my husband for over 600 days and am concerned for his health and well-being,” Rong said in a statement through Global Reach.

Chen’s work was part of a December 2020 study that looked at seismic data recorded across Asia, including China to improve methods for nuclear explosion monitoring and yield characterization.

The Global Reach further said: “There are suspicions within the US government that Chen’s arrest was spurred by China’s conduct of nuclear tests in violation of the Comprehensive Nuclear Test Ban Treaty."

The group further clarified that Chen’s expertise would give China “an opportunity to learn as much as possible about US seismic detection methodologies so they can develop countermeasures that allow them to circumvent the treaty.”

The treaty seeks to prohibit all nuclear tests on Earth, but several nuclear-capable states have not endorsed it. The US and China have both established voluntary moratoriums on explosive nuclear testing.

During Donald Trump’s first presidency, his administration accused Beijing of conducting a surreptitious underground test at the Lop Nur facility in northwestern China. In response, China rejected the claims as unfounded and politically motivated.

Furthermore, US Senator Edward Markey wrote in a statement published on Tuesday: “ It is hoped that increased attention on his unjust detention will force the Chinese government to do the right thing and release Chen.”