On Monday, a 78-year-old individual named John Shing-Wan Leung, who possesses both American citizenship and permanent residency in Hong Kong, was handed a life sentence in China.

He was convicted on spying charges in a trial conducted behind closed doors, with the public only becoming aware of the case recently. Leung’s arrest occurred in April 2021, and the specific details of the allegations against him have not been disclosed, as China keeps espionage trials confidential.

While the U.S. Embassy in Beijing acknowledged the conviction, they had not previously mentioned Leung’s arrest. The authorities in Hong Kong were informed of his detention in 2021.

“The Department of State has no greater priority than the safety and security of U.S. citizens overseas,” the embassy said.

Following Hong Kong’s transfer of sovereignty from British rule to Chinese control in 1997, the city maintained its own political system and freedoms for more than two decades. However, in 2020, the ruling Communist Party of China implemented a broad national security law, which utilized ambiguous language to effectively prohibit criticism of the party.

The sentencing of Leung is anticipated to further exacerbate the already strained relations between the United States and China. Prior to this incident, tensions were elevated when a Chinese military spy balloon drifted across U.S. territory earlier this year. The resulting fallout led to a three-month suspension of high-level meetings between the two countries, which was only recently resolved with a diplomatic discussion in Vienna.

Leung is not the sole foreign national detained in China on charges of espionage. Two Chinese Australians, Cheng Lei and Yang Jun, have been imprisoned since 2020 and 2019, respectively.