Deputy attorney general Rod Rosenstein said none of the Americans mentioned in the indictment of 13 foreign nationals were aware they were communicating with Russians about the presidential campaign.
The indictment shows Russian agents posed as Americans to conduct what they called "information warfare" against the U.S. by turning voters against certain candidates and sowing mistrust in political systems.
Special counsel Robert Mueller's investigators found those Russians communicated with "unwitting" Trump campaign officials and other political activists before and after the 2016 election.
Rosenstein explained that Russians helped organize competing rallies on the same day in New York City to both support President Donald Trump and protest him.
Three Russian companies were also named in the indictment.
Rosenstein said defendants purchased space on U.S. servers starting in 2014, set up a virtual private network and established hundreds of social media accounts using stolen or fictitious identities.
They purchased social media ads and promoted themes intended to help Hillary Clinton's election opponents, including Trump, Bernie Sanders and Jill Stein.
Rosenstein stressed the indictment did not show evidence that any of the Russian efforts were successful in shaping American voters' views.
WATCH: Deputy Atty. General Rod Rosenstein details how Russians were able to meddle in the 2016 election pic.twitter.com/HJ99s3228a— MSNBC (@MSNBC) February 16, 2018