Months after President Donald Trump took office, Russia‘s disinformation teams trained their sites on a new target: special counsel Robert Mueller III. Having worked to help get Mr Trump into the White House, they now worked to neutralise the biggest threat to his staying there.

The Russian operatives unloaded on Mr Mueller through fake accounts on Facebook, Twitter and beyond, falsely claiming that the former FBI director was corrupt and the allegations of Russian interference in the 2016 election were crackpot conspiracies. One post on Instagram – which emerged as an especially potent weapon in the Russian social media arsenal – claimed Mr Mueller had worked in the past with “radical Islamic groups.”

Such tactics exemplified how Russian teams ranged nimbly across social media platforms in a shrewd online influence operation aimed squarely at American voters. The effort started earlier than commonly understood and lasted longer while relying on the strengths of different sites to manipulate distinct slices of the electorate, according to a pair of comprehensive new reports prepared for the Senate Intelligence Committee and released on Monday.

One of the reports, written by Oxford University’s Computational Propaganda Project and network analysis firm Graphika, became public when The Washington Post obtained it and published its highlights on Sunday. The other report was by social media research firm New Knowledge, Columbia University and Canfield Research.

Together the reports described the Russian campaign with sweep and detail not before available. The researchers analysed more than 10 million posts and messages on every major social media platform to understand how the Russians used American technology to build a sprawling online disinformation machine, with each piece playing a designated role while supporting the others with links and other connections.

The reports also underscore the difficulty of defeating Russian disinformation as operatives moved easily from platform to platform, making the process of detecting and deleting misleading posts impossible for any company on its own to manage.

Twitter hit political and journalistic elites. Facebook and its advertising targeting tools divided the electorate into demographic and ideological segments ripe for manipulation, with particular focus on energising conservatives and suppressing African-Americans, who traditionally are more likely to vote for Democrats.

YouTube provided a free online library of more than 1,100 disinformation videos. PayPal helped raise money and move politically-themed merchandise designed by the Russian teams, such as “I SUPPORT AMERICAN LAW ENFORCEMENT” T-shirts. Tumblr, Medium, Vine, Reddit and various websites also played roles.

“We hope that these reports provide clarity for the American people and policymakers alike, and make clear the sweeping scope of the operation and the long game being played,” said Renee DiResta, research director at New Knowledge.

Social media researchers said the weaponisation of these sites and services highlights the broadening challenge they face in combating the increasingly sophisticated tactics of Russia and other foreign malefactors online.

“Some of the platforms that don’t have as much traffic, but still have highly engaged communities, are the most vulnerable to a challenge like misinformation,” said Graham Brookie, head of the Atlantic Council’s Digital Forensic Research Lab. “They don’t have the resources to dedicate to making their platforms more resilient.”

One unexpected star of the new reports on Monday was Facebook’s photo-sharing subsidiary Instagram. Over the years of the disinformation campaign, Instagram generated responses on a scale beyond any of the others – with 187 million comments, likes and other user reactions, more than Twitter and Facebook combined.

But it had been the least scrutinised of the major platforms before this week as lawmakers, researchers and journalists focused more heavily on Facebook, Twitter and Google. Instagram’s use by the Russians more than doubled in the first six months after Mr Trump’s election, the researchers found. It also offered access to a younger demographic and provided easy likes in a simple, engaging format.

“Instagram’s appeal is that’s where the kids are, and that seems to be where the Russians went,” said Philip Howard, head of the Oxford research group.

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He favours gun regulations and was a signatory to a letter from some 400 mayors condemning President Trump's withdrawal from the Paris Climate Accord. Vice News Who could be running against Trump in 2020? Kirsten Gillibrand The New York Senator formally announced her presidential bid in January, saying that “healthcare should be a right, not a privilege.” Getty Who could be running against Trump in 2020? Cory Booker The New Jersey Senator has announced that he will be running for the presidency in 2020. If he secures the nomination he said finding a female vice president would be a priority. Getty Who could be running against Trump in 2020? John Delaney The Maryland congressman was the first to launch his bid for presidency, making the announcement in 2017. AP Who could be running against Trump in 2020? Julian Castro The former San Antonio mayor announced his candidacy in January and said that his running has a “special meaning” for the Latino community in the US. 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The report anchored by New Knowledge found the Russians posted on Instagram 116,000 times, nearly double the number of times they did on Facebook, as documented in the report. The most popular posts praised African-American culture and achievement, but the Russians also targeted this community for voter suppression messages on multiple platforms, urging boycotts of the election or spreading false information on how to vote.

On Monday, the National Association for the Advancement of Coloured People called for a week-long boycott of Facebook starting on Tuesday, saying the company’s business practices – and the spread of “disingenuous portrayals of the African-American community” on its site – should prompt further congressional investigation.

Facebook said in a statement that it has “made progress in helping prevent interference on our platforms during elections, strengthened our policies against voter suppression ahead of the 2018 midterms, and funded independent research on the impact of social media on democracy.”

Reddit said it is “always evaluating and evolving our approaches to detecting malicious activity and have grown our team significantly since 2016.” Medium did not immediately respond to requests for comment. Tumblr pointed to a November blog post, which said the company took down Russian-related disinformation ahead of the 2018 election. PayPal said it “works to combat and prevent the illicit use of our services.” Twitter said it has made “significant strides since 2016 to counter manipulation of our service.”

The emergence of Mr Mueller as a significant target also highlights the adaptability of the Russian campaign. He was appointed in May 2017 as special counsel to investigate allegations of Russian influence on the Trump campaign. In that role, he has indicted the St Petersburg-based Internet Research Agency, the Kremlin-linked troll farm behind the disinformation campaign, and others affiliated with the disinformation campaign on criminal charges.

A Clemson University research team, not affiliated with either of the reports released on Monday, found that the Russians tweeted about Mr Mueller more than 5,000 times, including retweets first posted by others. Some called for his firing, while others mocked him as incompetent and still others campaigned for the end of his “entire fake investigation.”

Donald Trump will sit down with Robert Mueller 'only over my dead body' says Rudy Giuliani

The report by New Knowledge highlighted the focus on Mr Mueller and fired FBI director James Comey, who was falsely portrayed as “a dirty cop.”

The Russian operatives often spread jokes to undermine the investigations into their disinformation campaign, the researchers found. One showed Democrat Hillary Clinton saying, “Everyone I don’t like is A Russian Hacker.” Another showed a woman in a car talking to a police officer, with the caption, “IT’S NOT MY FAULT OFFICER, THE RUSSIANS HACKED MY SPEEDOMETER.”

At one point, shortly after the 2016 election, the Russian operatives also began to make fun of Facebook CEO Mark Zuckerberg for saying social media did not have an impact on Mr Trump’s victory – a claim for which he later apologised.

On Capitol Hill, top Democrats said on Monday that the revelations in the pair of Senate reports underscored the need to study social media and consider fresh regulation in order to stop Russia and other foreign actors from manipulating American democracy in future elections.

“I think all the platforms remain keenly vulnerable, and I don’t have the confidence yet companies have invested the resources and people power necessary to deal with the scope of the problem,” said Representative Adam Schiff, D-Calif, the incoming chairman of the House Intelligence Committee.

In particular, Mr Schiff described the Instagram revelations as “surprising,” contradicting the data and testimony Facebook previously provided to the committee. “If Facebook was unaware of it, it’s one problem,” he said. “If they were aware of it and didn’t share that information, that’s a completely different problem.”

Senator Richard Burr, R-NC, the chairman of the committee that asked the researchers to analyse the tech companies’ data, said the findings show “how aggressively Russia sought to divide Americans by race, religion and ideology.”

Every other GOP lawmaker on the Senate Intelligence Committee declined to comment or did not respond.

Facebook executives barely discussed the role of Instagram when they testified before Congress late last year about Russian meddling. At the time, the company said the Russian campaign reached 126 million people on Facebook and 20 million on Instagram.