Joshua Schulte, a former CIA officer, was sentenced to 40 years in prison for disclosing a large amount of classified information that he provided to the WikiLeaks platform.
He was also found guilty of possessing child abuse photographs.
Prosecutors accused him of leaking information related to CIA tools that allow intelligence officials to hack into smartphones and use them as eavesdropping devices.
The data leak is one of the "brazenest" in American history, prosecutors said.
- What did WikiLeaks discover about Serbia?
- How leaked documents from the Pentagon spread on the Internet
- Who is Jack Teichera, suspected of leaking classified intelligence documents
Schulte provided about 8.761 documents to WikiLeaks in 2017, the largest leak in CIA history, the US Department of Justice said.
He denied the charges, but was convicted on different counts in three separate federal trials in New York in 2020, 2022 and 2023.
The court found him guilty of espionage, computer hacking, contempt of court, making false statements to the Federal Bureau of Investigation (FBI) and possessing child abuse photographs.
"Joshua Schulte betrayed his own country by committing some of the most brazen, heinous crimes of espionage in American history," said Damian Williams, the US attorney.
According to evidence presented at trial, Schult worked as a software developer at the Center for Cyber Intelligence, which conducts cyber espionage against terrorist organizations and foreign governments.
Prosecutors said he provided stolen information to WikiLeaks in 2016 and then lied to FBI agents about his own role in the leak.
It is added that he was motivated by anger over a dispute at the workplace.
He struggled to meet deadlines, and Assistant U.S. Attorney Michael Lockard said one of his projects was so late it was nicknamed the "Drifting Line."
Prosecutors said he wanted to punish those he believed had wronged him and said that "by carrying out that revenge, he caused enormous damage to the country's national security."
WikiLeaks began releasing classified information from the files in 2017.
The leak, prosecutors said, "immediately damaged the CIA's ability to gather foreign intelligence, and the damage caused is estimated to be in the hundreds of millions of dollars."
The FBI interviewed Schult several times before WikiLeaks released the information, and he denied responsibility.
During the search of his apartment, tens of thousands of photographs of sexually abused children were discovered.
It is stated that Schult tried to provide even more information during the arrest.
He smuggled a phone into the prison trying to send a reporter information about CIA cyber groups.
He also leaked information about CIA cyber tools on Twitter under the name Jason Bourne, a fictional intelligence operative.
Schult has been in prison since 2018.
Watch the video - Who is Julian Assange
Follow us on Facebook, Twitter i Viber. If you have a topic proposal for us, contact us at bbcnasrpskom@bbc.co.uk
Bonus video:
