The US justice department has indicted 12 Russian intelligence officers for hacking the Democratic National Committee in the 2016 election.
Deputy Attorney General Rod Rosenstein said the dozen accused used spear phishing emails and malicious software in the cyber-attacks.
Special Counsel Robert Mueller’s inquiry is looking into alleged Russia meddling in the 2016 election.
The investigation has already indicted 20 people and three companies.
The indictment says the named Russian intelligence officers began their cyber-attacks in March 2016 to hack the email accounts of volunteers and employees of Hillary Clinton’s presidential campaign.
Mr Rosenstein said the defendants corresponded with several Americans during the alleged conspiracy, but added there is no allegation that any US citizen committed a crime.
The deputy attorney general said the defendants worked for two units of the Russian intelligence service, the GRU.
The alleged conspirators hacked into the computer network of the Democratic Congressional Committee and Democratic National Campaign Committee.
He said: “The defendants covertly monitored the computers, implanted hundreds of files containing malicious computer code, and stole emails and other documents.”