The State Department announced the release of Mark Swidan, Kai Li and John Leung. A U.S. government official told NBC News the three were exchanged for Chinese detainees.

The plight of Americans facing exit bans in China show the enduring risks of getting caught in the country’s murky legal system.

Three American citizens imprisoned for years by China arrived back in the United States late Wednesday. Their release, announced earlier by the White House, was the result of a rare diplomatic agreement with Beijing in the final months of the Biden administration.

The sentencing of Dong Yuyu, a former Harvard Nieman fellow, signals that officials consider some exchanges between Chinese citizens and foreigners to be espionage.

Dong Yuyu is a liberal voice who had engaged frequently with diplomats, scholars and journalists from the U.S. and Japan.

Chinese journalist Dong Yuyu was sentenced in a Beijing court to seven years in prison for espionage after meeting with a Japanese diplomat at a restaurant.