Russian internet trolls’ “most prolific” endeavor to influence the 2016 election was their effort to use social media to target black Americans, who they then sought to discourage from voting, a new report assembled for the Senate Intelligence Committee found.

The analysis, first reported on by the New York Times Monday and published in full by Axios, said that the American Black community was targeted “extensively” with “dozens” of Facebook Pages or Instagram accounts, compared with just one or two phony accounts aimed at other ethnic or religious groups, the analysis said. The Senate Intelligence Committee officially released the report, as well as a related reported on the Russian internet trolls, on Monday morning.

“[T]his is why we have elected to assess the messaging directed at Black Americans as a distinct and significant operation for the purposes of the report,” reads the report from the Austin, Texas cybersecurity firm New Knowledge and researchers at Columbia University and Canfield Research LLC.

The New Knowledge report said that the Russians’ voter suppression efforts on social media could be broken down into three categories: “malicious misdirection,” which were efforts to confuse users about voting rules; encouragement that users vote for a third party, rather than for Hillary Clinton or Donald Trump; and recommendations that voters stay home altogether.

It’s not clear exactly how successful the Russians’ black voter suppression campaign was, but as the New York Times noted, in 2016 African American voting rates declined for the first time in two decades.

Unlike the social media messaging aimed at left- and right-leaning Americans, the accounts geared towards black Americans largely ignored the election in the weeks leading up to the 2016 election, according to the report. However, those accounts continued to emphasize “themes about social alienation and police brutality.”

“As the election became imminent, those themes were then tied into several varieties of voter suppression narratives: don’t vote, stay home, this country is not for Black people, these candidates don’t care about Black people,” the New Knowledge report said.

The fake accounts were created by a Kremlin-backed troll farm in Russia called the Internet Research Agency. Special counsel Robert Mueller has brought charges against individuals and entities who allegedly helped organize, run and fund the operation.

Compared to the efforts aimed at left- and right-leaning communities, Russian social media trolls went to greater lengths to ingratiate themselves with the African American online community, the New Knowledge report found, aiming to earn the community’s’ trust, which it was then able to exploit. There were 30 phony Facebook pages, among the the 81 provided to the Senate committee, that were geared at the black community — compared to 25 pages for a conservative audience and just seven pages for liberal users, the report said.

One Russian-created social media account, Black Matters, posted job listings for real Americans to create content for the page, according to the report. On Instagram, the Russian trolls pushed merchandise — and even offered coupons to those who shared their content — that was targeted towards the black community, using hashtags like #SupportBlackBusiness and #BuyBlack, according to the report.

The bulk of content the Internet Research Agency created for YouTube was also geared toward a black audience, with Black Lives Matter- and policy brutality-themed content making up 59 percent of the channels and 96 percent of the content, per the report.

Another element of Russians’ targeting of black Americans, which separated the operation from the campaigns geared at left and right communities, was the use of what New Knowledge called “media mirage.” The phony Russian pages were interlinked with other phony accounts for the black community, as well as to authentic African American social media pages.

“An individual who followed or liked one of the Black-community-targeted IRA pages would have been exposed to dozens more, as well as carefully-curated authentic Black media content that ideologically or thematically aligned with the Internet Research Agency messaging,” the report said.

A New Knowledge interactive map outlining how the phony accounts linked to authentic accounts for the black community is available here.

The use of “media mirage” was much more minimal for the pages targeting left- and right-leaning audiences, per the report.

In a statement on the report, Senate Intelligence Committee Chair Richard Burr (R-NC) said that the findings “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.”

The NAACP’s Legal Defense Fund issued a statement blasting the Trump administration’s failure to address the kind of voter suppression efforts described in the report released on Monday.

“These extraordinary revelations should be of the gravest concern to anyone who cares about the integrity of our elections and the health of our democracy. We now know that Black American voters must contend with both overwhelming domestic suppression effort, as well as foreign interference on a massive scale. These threats are not separate phenomena. They are closely related attempts to use race and racism in America to divide the electorate and subjugate Americans of color,” Sherrilyn Ifill, the president and director-counsel for the NAACP LDF, said in the statement.

“For years, we have urged Congress and this administration to investigate and address voter suppression targeting voters of color. Instead, the Trump Administration has chosen to pursue false allegations of in-person vote fraud,” she added. “We urge the House Oversight Committee to investigate these revelations in the new year, so that we can begin to take the steps necessary to protect voting rights from the many assaults it now faces.”

Read the report:

