Chinese-born American seismologist Youlin Chen is detained in China and faces trial on spying charges, according to his wife, U.S. lawmakers, and hostage advocacy groups. The reports say Chen, 54, has published U.S.-funded work related to detecting North Korean nuclear tests. His wife, Yufang Rong, and others describe his detention as lasting nearly two years and say the Trump administration has emphasized securing his release through high-level diplomacy rather than a public announcement.

The case is described as adding strain to relations among China, the United States, and North Korea, which remain sensitive amid ongoing nuclear concerns. U.S. officials say Chen’s situation has become a priority for Washington. On March 19, Secretary of State Marco Rubio designated Chen as “wrongfully detained,” according to the Korea Times. A U.S. source familiar with the matter is cited as saying the administration is focused on gaining his release from what it calls an unjustifiable detention.

The outlets note that Chen’s background and publications are central to U.S. concerns, while China maintains that he is facing spying-related charges.