BEIJING  —China has sentenced a 78-year-old US citizen, John Shing-Wan Leung, to life imprisonment on charges of spying.

Leung, who holds permanent residency in Hong Kong, was detained in April 2021 by the counterintelligence agency in Suzhou. The details of the charges have not been made public, as such investigations and trials are held behind closed doors.

The strained relations between Washington and Beijing, due to disagreements over trade, technology, human rights, and territorial claims, have hit a historical low.

The sentencing comes as President Joe Biden is attending the G7 summit in Japan and is set to visit Papua New Guinea, a Pacific island nation where China has been increasing its economic, military, and diplomatic influence.

Although the Suzhou court did not mention any connection between Leung's case and the broader China-U.S. relations, spying charges are usually used selectively and evidence to support them is not typically made public.

This is a standard practice in many countries, as it helps to protect their personal connections, networks, and access to information.

However, China's authoritarian political system and the Communist Party's complete control over legal matters, civil society, and freedom of information make it difficult to demand additional information or file court appeals.