A former Central Intelligence Agency officer has been arrested on charges of conspiring with a relative, who also worked for the CIA, to spy for China.
Alexander Yuk Ching Ma, 67, was arrested on Friday and charged, said the US justice department.
He is accused of divulging classified national defence information to Chinese intelligence officials.
It is the latest espionage arrest at a time of growing tension between Washington and Beijing.
Mr Ma is due to appear in court on Tuesday and faces a maximum penalty of life imprisonment if convicted.
What do we know about Mr Ma?
Mr Ma, a naturalised US citizen born in Hong Kong, began working for the CIA in 1982.
Prosecutors said he left the CIA seven years later and worked in the Chinese city of Shanghai before moving to Hawaii in 2001.
They accuse Mr Ma and his relative of spying for China over the course of a decade in a scheme that began with meetings in Hong Kong in March 2001.
The ex-CIA officers are accused of sharing information "about the CIA's personnel, operations, and methods of concealing communications" with the Chinese intelligence service.
Part of their meeting in Hong Kong was recorded on videotape and shows Mr Ma counting $50,000 (£38,000) in cash for the secrets they shared, the statement said.
While living in Hawaii, court documents say, he then sought work with the FBI to gain access to classified US government information once again to pass on to China.
He was hired by the FBI's Honolulu office in 2004 as a contract linguist and is accused of stealing documents marked secret.
It remains unclear why it took so long to arrest Mr Ma.
The unnamed relative with whom prosecutors say Mr Ma conspired is now 85-years-old. He is also a naturalised US citizen, who was born in Shanghai.
Court documents say prosecutors are not seeking an arrest warrant for him at this time as he is suffering from an "advanced and debilitating cognitive disease".
What are the other espionage cases?
This is the latest arrest in a string of cases against former intelligence officers.
In November another former CIA officer, Jerry Chun Shing Lee, was sentenced to 19 years in prison for conspiring to spy for China.
The information shared by Mr 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 in one of the most disastrous failures of US intelligence in recent years.
In May 2019, Kevin Mallory, another ex-CIA agent, 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.
In Monday's statement Assistant Attorney General for National Security John C. Demers said: "The trail of Chinese espionage is long and, sadly, strewn with former American intelligence officers who betrayed their colleagues, their country and its liberal democratic values to support an authoritarian communist regime."
"Whether immediately, or many years after they thought they got away with it, we will find these traitors and we will bring them to justice."
Why are tensions especially high now?
The relationship between the US and China has plummeted to its lowest point in decades.
They've been locked in a bitter trade war since 2018 and earlier this month US President Donald Trump threatened to ban the popular Chinese app TikTok.
The two economic superpowers have also clashed over the coronavirus pandemic and the controversial new security law imposed by Beijing in Hong Kong.
Last month a Singaporean man pleaded guilty in the US to working as an agent of China.
According to court documents he was recruited by Chinese intelligence in 2015, when he was a PhD student at a prestigious Singaporean university, after giving a presentation in Beijing.
Jun Wei Yeo, also known as Dickson Yeo, was charged with using his political consultancy in America as a front to collect information for Chinese intelligence.
The US has also been pursuing economic espionage charges against China in recent years.
About 80% of all economic espionage prosecutions brought by the justice department "allege conduct that would benefit the Chinese state", the department says on its website.