A former CIA agent has been sentenced to 19 years in prison for conspiring to spy for China.
Jerry Chun Shing Lee, 55, left the CIA in 2007 and was recruited by Chinese agents in Hong Kong. Prosecutors say he was then paid to divulge information on US national defence.
China is then said to have dismantled a network of informants.
Lee is the third former CIA officer in less than a year to be sentenced for conspiring with China.
He pleaded guilty in May to conspiracy to deliver national defence information to aid a foreign government.
But prosecutors and defence lawyers disagreed over the extent of the crime, with Lee - a naturalised US citizen - seeking a lesser sentence of 10 years.
Prosecutors said Chinese intelligence officers gave Lee hundreds of thousands of dollars and that he likely gave them all the information he had from his 13-year career in the CIA.
But his defence team argued that it was never proved that the money came from China or that he carried out plans to deliver government secrets.
US attorney Zachary Terwilliger welcomed Friday's sentencing.
"Lee sold out his country, conspired to become a spy for a foreign government, and then repeatedly lied to investigators about his conduct," he said in a statement.
What's the background?
The justice department says Lee was contacted by Chinese intelligence agents in 2010. They offered him money, promising to take care of him "for life" in exchange for the required secret information.
Hundreds of thousands of dollars were deposited in his Hong Kong bank account between May 2010 and December 2013.
Lee created a document containing information about CIA activities, including locations to which US agents would be assigned.
In 2012, FBI agents searched a hotel room in Hawaii registered in Lee's name and found a USB drive. Investigators found the document on unallocated space in the drive, suggesting it had been deleted.
The search also revealed Lee to have a day planner and address book containing notes of intelligence provided by CIA agents, their true identities, operational meeting locations and phone numbers, and information about covert facilities.
Lee was interviewed by CIA officers in 2012 during which he said he had met Chinese intelligence officers but concealed the fact that they had set him tasks, the justice department said. In 2013 he first denied knowing about the document on his USB drive and then admitted he had created it but said he had never handed it on to Chinese agents.
He was arrested at New York's JFK airport in January 2018.
How significant is the case?
The information provided by Lee is said to have helped China to bring down a network of informants between 2010 and 2012.
About 20 informants were killed or jailed during that period - one of the most disastrous failures of US intelligence in recent years.
Lee is not the only former CIA officer to be convicted of working with China.
In May, former CIA spy Kevin Mallory was sentenced to 20 years in prison, after being convicted of conspiring to transmit US defence secrets to China.
Former US intelligence officer Ron Rockwell Hansen was sentenced in September to 10 years in prison.