The Russian government's efforts to influence the 2016 presidential election were sprawling, multifaceted and sophisticated, affecting millions of users in the U.S. and persisting long after the election was over, two independent analyses revealed Monday.

Some content that was initiated by the Russian government, operating through the Internet Research Agency (IRA), still lives on social media platforms here and the Kremlin's interference operations are likely to continue – now and through 2020, experts found.

The extensive reports, one authored by cybersecurity firm New Knowledge, the other jointly by the University of Oxford researchers and Graphika, which specializes in social media analysis, are the first of their kind to detail the kinds of active measures Russian actors employed to exploit social divisions, grow distrust in the U.S. government and media outlets, and erode voters' confidence in democratic processes.

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They were crafted chiefly on the basis of data provided by social media companies to the Senate Select Committee on Intelligence, which is conducting an investigation into Russia's interference in 2016. The Committee welcomed the research effort without endorsing either report's findings.

"This newly released data demonstrates how aggressively Russia sought to divide Americans by race, religion and ideology, and how the IRA actively worked to erode trust in our democratic institutions," Senate Intelligence Committee Chairman Richard Burr, R-N.C., said in a statement. "Most troublingly, it shows that these activities have not stopped," he said.

"These attacks against our country were much more comprehensive, calculating and widespread than previously revealed," added Democrat Vice Chairman Mark Warner, D-Va. "This should stand as a wake up call to us all that none of us are immune from this threat, and it is time to get serious in addressing this challenge."

The Oxford report, which also drew from data provided to the House Permanent Select Committee on Intelligence, said IRA's activities began on Twitter in 2013, before evolving into a "multi-platform strategy" that included Facebook, Instagram, YouTube and other platforms.

"The scale of their operation was massive," New Knowledge's authors wrote, citing the 126 million Facebook users and 20 million Instagram users whom they estimated were reached by IRA content. The IRA's efforts also included posting more than 10.4 million tweets and 1,000 YouTube videos, as well as targeting other, less prominent platforms, including Tumblr, Reddit and Pinterest.

Though much of the content was politically charged or conspiratorial, researchers found extensive operations targeting African-American communities in particular.

"The most prolific IRA efforts on Facebook and Instagram specifically targeted Black American communities," New Knowledge's report said, "and appear to have been focused on developing Black audiences and recruiting Black Americans as assets."

The report included new details on the ways in which IRA operatives engaged in direct outreach and recruitment of American citizens, coaxing them to protest or perform specific jobs or tasks, and even attempting to forge personal connections around difficult personal struggles like sex addiction.

Both the New Knowledge and Oxford reports found the disinformation efforts persisted even after the election ended, and that engagement rates with content covering a wide range of policy, national security and other social issues increased. Facebook and Instagram posts targeting right-wing users and mocking the idea of Russian interference as well as the media outlets that covered it sprouted up in the election's immediate aftermath.

"What we've seen here is a sophisticated operation that does not hesitate to reach out to individual Americans, that does not hesitate to turn them into unwitting tools of the Russian government," said Renee DiResta, one of the principal authors of New Knowledge's report. "We believe they are going to spend less time creating their own, easily-detectable pages in bad English, and begin engaging in even more targeted outreach, including by infiltrating political fringe groups to opportunistically exploit divisions."

Notably, the reports' conclusions support those of the Intelligence Community Assessment issued in 2017, which found with high confidence that Russian president Vladimir Putin and his government developed a "clear preference" for Donald Trump.

The conclusions are at odds with previous public statements made by some Trump administration officials, including Department of Homeland Security Secretary Nielsen, who has said repeatedly that Russia's goal was primarily to sow division among the U.S. electorate.

"What is clear is that all of the messaging clearly sought to benefit the Republican Party—and specifically, Donald Trump," the Oxford report authors wrote. "While the IRA strategy was a long-term one, it is clear that activity between 2015 and 2016 was designed to benefit President Trump's campaign."

"The IRA had a very clear bias for then-candidate Trump that spanned from early in the campaign and throughout the data set," the New Knowledge report said, citing political content that began in the early primaries.

The Senate Intelligence Committee issued a bipartisan finding earlier this year that confirmed the intelligence community's assessment; the House Intelligence Committee's Republican-issued final report on Russian interference cast doubt on whether Putin's strategic objective was indeed to help elect Mr. Trump.

Both reports were also critical of some social media companies for being uncooperative or evasive in their dealings with Congress. New Knowledge said Facebook and Twitter handed over needlessly opaque or limited data sets and may have "misrepresented" some findings in statements they made while testifying.

"Instagram was a significant front in the IRA's influence operation, something that Facebook executives appear to have avoided mentioning in Congressional testimony," New Knowledge's authors observed.

The companies' reluctance to be forthcoming with data, the researchers said, "hints at the possibility of deciding to provide the bare minimum possible to meet the Committee's request."

Facebook released a statement to CBS News Monday saying that it continues "to fully cooperate with officials investigating the IRA's activity on Facebook and Instagram around the 2016 election." The social media giant also pointed to the "thousands of ads and pieces of content" it has provided to the Senate Intelligence Committee for review and "shared information with the public about what we found." Facebook also said that it "made progress" in helping to prevent further election interference on its platforms before the 2018 elections.

Twitter, too, responded with a statement saying, "We've made significant strides since 2016 to counter manipulation of our service, including our release of additional data in October related to previously disclosed activities to enable further independent academic research and investigation."

As part of its ongoing investigation, the Senate Intelligence Committee is expected to release its own report on social media influence efforts, along with others focused on the Obama administration's response to Russia's activities and on whether members of the Trump campaign colluded with representatives of the Russian government.