Private experts has revealed that Russian interference in the 2016 US presidential election on social media was more widespread than previously thought and included attempts to divide Americans by race and extreme ideology.
The Russian government's Internet Research Agency, based in St Petersburg, Russia, tried to manipulate US politics, said the reports, one by social media analysts New Knowledge and the other by an Oxford University team working with analytical firm Graphika.
The twin reports largely verified earlier findings by US intelligence agencies, but offered much more detail about Russian activity going back years that continues even now.
For instance, one Russian troll farm tried to encourage US "secessionist movements" in California and Texas, the New Knowledge report said.
"What they tried to do is divide US public opinion by the existing divisions that were there."
Richard Burr, the Republican chairman of the US Senate Intelligence Committee, said in a statement that the new "data demonstrates how aggressively Russia sought to divide Americans by race, religion and ideology".
The Russian agency worked to erode trust in US democratic institutions and its activities have not stopped, he said.
The committee collected data from social media companies that was used by the private analysts in their analysis.
Senator Mark Warner, the committee's top Democrat, said, "These reports demonstrate the extent to which the Russians exploited the fault lines of our society to divide Americans in an attempt to undermine and manipulate our democracy.
"These attacks ... were much more comprehensive, calculating and widespread than previously revealed," he said.
Targeted African Americans
Oxford/Graphika said the Russians spread "sensationalist, conspiratorialist, and other forms of junk political news and misinformation to voters across the political spectrum."
The group said Russian trolls urged African Americans to boycott the election or to follow wrong voting procedures, while also encouraging right-wing voters to be more confrontational.
Since Donald Trump was elected President in 2016, it said, Russian trolls have put out messages urging Mexican-American and other Hispanic voters to mistrust US institutions.
The report from New Knowledge said the Russians ran "comprehensive Anti-Hillary Clinton operations," such as efforts to organize Muslims to stage a pro-Clinton demonstration.
The report said Russian hackers also targeted Republican senators Ted Cruz, Marco Rubio, Lindsey Graham and the late John McCain, as well as former FBI chief James Comey, special prosecutor Robert Mueller, and WikiLeaks founder Julian Assange.
The matter is being investigated by Special Counsel Mueller, whose long-running inquiry has clouded the Trump presidency and netted guilty pleas and indictments against former close Trump associates.
Social media, games, apps
Another major takeaway from both studies is the breadth of Russian interference that appeared on Instagram, which is owned by Facebook and was not frequently mentioned when its parent company testified on Capitol Hill.
The study says that as attention was focused on Facebook and Twitter in 2017, the Russians shifted much of their activity to Instagram.
The New Knowledge study says that there were 187 million engagements with users on Instagram, while there were 77 million on Facebook.
"Instagram was a significant front in the IRA's influence operation, something that Facebook executives appear to have avoided mentioning in congressional testimony," the researchers wrote.
They added that "our assessment is that Instagram is likely to be a key battleground on an ongoing basis."
The Russian activity went far beyond the three tech companies that provided information, reaching many smaller sites as well.
The New Knowledge report details sophisticated attempts to infiltrate internet games, browser extensions and music apps.
The Russians even used social media to encourage users of the game Pokemon Go - which was at peak popularity in the months before the 2016 presidential election - to use politically divisive usernames, for example.
The report discusses even more unconventional ways that the Russian accounts attempted to connect with Americans and recruit assets, such as merchandise with certain messages, specific follower requests, job offers and even help lines that could encourage people to unknowingly disclose sensitive information to Russia that could later be used against them.
The Russians' attempts to influence Americans on social media first became widely public in the fall of 2017.
Several months later, Mueller's indictment laid out a vast, organised Russian effort to sway political opinion.
While the social media companies had already detailed some of the efforts, the indictment tied actual people to the operation and named 13 Russians responsible.
The Kremlin has denied the allegations of meddling.
Trump has denied any collusion between Russia and his campaign.