Charges are set to be announced against four defendants, including two Russian security services officers, over a massive data breach at internet giant Yahoo.
A US official said two of the defendants are Russian FSB officers and the other two are criminal hackers.
One of the defendants has been taken into custody in Canada.
The US justice department is expected to publicly announce the charges later on Wednesday.
The charges arise from a 2014 compromise of Yahoo user accounts and would be the first case brought against Russian government officials.
The announcement comes as federal authorities investigate Russian interference through hacking in the 2016 presidential election.
Yahoo did not disclose the 2014 breach until last September when it began notifying at least 500 million users that their email addresses, birth dates, answers to security questions and other personal information may have been stolen.
Three months later, Yahoo revealed it had uncovered a separate hack in 2013 affecting about one billion accounts, including some that were also hit in 2014.
Acting Assistant Attorney General Mary McCord said: "We will not allow individuals, groups, nation states or a combination of them to compromise the privacy of our citizens, the economic interests of our companies, or the security of our country."
In a statement, Chris Madsen, Yahoo's assistant general counsel and head of global security, thanked law enforcement agencies for their work.
"We're committed to keeping our users and our platforms secure and will continue to engage with law enforcement to combat cybercrime," he said.