Thirteen Russians have been charged with interfering in the US 2016 election, in a major development in the FBI investigation.
Three of those named have also been accused of conspiracy to commit wire fraud and five have been accused of aggravated identity theft.
The announcement was made by Special Counsel Robert Mueller, who is investigating alleged Russian meddling.
Three Russian companies are also named in the indictment.
One of them is the Internet Research Agency, based in St Petersburg, which the 37-page indictment said "had a strategic goal to sow discord in the US political system, including the 2016 US presidential election".
Speaking at a news conference, Deputy Attorney General Rod Rosenstein said there was no allegation that any American was "a knowing participant in this illegal activity" nor was it alleged that the meddling altered the election outcome.
Russia has repeatedly denied interfering in the US presidential election.
What does the indictment say?
It says a group of Russians:
Posed as Americans, and opened financial accounts in their name
Spent thousands of dollars a month buying political advertising
Purchased US server space in an effort to hide their Russian affiliation
Organised and promoted political rallies within the United States
Posted political messages on social media accounts that impersonated real US citizens
Promoted information that disparaged Hillary Clinton
Received money from clients to post on US social media sites
Created themed groups on social media on hot-button issues, particularly on Facebook and Instagram
Operated with a monthly budget of as much as $1.25m (£890,000)
Financed the building of a cage large enough to hold an actress portraying Hillary Clinton in a prison uniform
The indictment says those involved systematically measured how well their internet posts were doing and adjusted their strategies to maximise effectiveness.
It also says those named in the indictment had visited the US posing as American citizens and had begun discussing how to affect the election as early as 2014.
What is the investigation about?
US intelligence agencies believe Russia tried to sway the 2016 presidential election in favour of Republican candidate Donald Trump.
In May last year, Mr Mueller was appointed special counsel to investigate whether anyone from his campaign colluded in the effort.
As part of the inquiry, former Trump campaign manager Paul Manafort has been charged with conspiring to defraud the US in his dealings with Ukraine, and conspiracy to launder money.
A business associate of his, Rick Gates, was also charged with conspiracy to launder money. A third adviser to the Trump campaign, George Papadopoulos, pleaded guilty to lying to the FBI.
This week President Trump's former chief strategist, Steve Bannon, was interviewed by Mr Mueller.
Mr Trump has been accused by opponents of trying to interfere with the investigation.The president denies this - as well as any allegation of collusion with Russia during the campaign.