BEIJING — China sentenced a 78-year-old United States citizen to life in prison Monday on spying charges.

John Shing-Wan Leung, who holds permanent residency in Hong Kong, was detained April 15, 2021, by the counterintelligence agency in the southeastern city of Suzhou. The city’s intermediate court announced Leung’s sentence in a brief statement on its social media site but gave no details of the charges.

Such investigations and trials are held behind closed doors and little or no information is made public.

Relations between Washington and Beijing have hit a historical low amid disputes over trade, technology, human rights and China’s increasingly aggressive approach toward its territorial claims.