The major social media companies whose platforms were used by the Russian government to sharpen division in the United State before and after the 2016 election had an “uncoordinated” response to the influence campaign and did not fully cooperate with government investigations, a new report on the effort claimed.

“Social media firms need to co-operate with public agencies in a way that respects users’ privacy,” read the report for the Senate Intelligence Committee released Monday. “However, sharing data about public problems should be more than performative, it should be meaningful and constructive.”

The report – compiled by Oxford University’s Computational Propaganda Project – singles out Facebook and Google for either presenting limited information or handing over data in an unnecessarily burdensome way.

Google, for example, “chose to supply the Senate committee with data in a non-machine-readable format,” even though the data – Google ads that the Internet Research Agency had bought – was “previously organized in spreadsheets.”

“Google’s disruption efforts are impossible to audit and contrast with Facebook’s and Twitter’s efforts given the sparse data provided,” the report reads.

Facebook, on the other hand, provided limited information that forced the scope of the investigation to be narrowed. The social media network “chose not to disclose data” from specific Internet Research Agency “profiles or groups” but instead provided data from “a small number of pages” to Senate investigators.

The bulk of the report details how far the Russian trolls – working at St. Petersburg’s Internet Research Agency – gained influence in U.S. politics by amassing millions of shares and views on social media posts.

The report states that the trolls aimed at stoking division and increasing polarization in the United States while discouraging traditional Democratic constituencies from voting, most notably African-Americans.

On Facebook, for example, the five most shared and liked posts “focused on divisive issues, with pro-gun ownership content, anti-immigration content pitting immigrants against veterans, content decrying police violence against African Americans, and content that was anti-Muslim, anti-refugee, anti-Obama, and pro-Trump.”

In some cases, trolls campaigned for “African American voters to boycott elections or follow the wrong voting procedures” and attempted to encourage “extreme right-wing voters to be more confrontational.”

The report argues that the Russian trolls used existing divides in the U.S. political system to achieve a wide scope in their disinformation campaign.

“Explicit mentions of Donald Trump increased in early and mid-2016, as his primary campaign gained momentum,” the researchers write. “These campaigns, however, seemed to be geared towards extending the anti-immigrant rhetoric that Trump’s campaign frequently made use of.”

The campaign reached tens of millions of Americans, with more than 30 million sharing the IRA’s Facebook posts between 2015 and 2017, the period covered by the report.

And though the report takes no position on whether the Russian influence campaign changed the outcome of the election, the researchers argue that the use of “computational propaganda” – where people can be individually targeted and manipulated by algorithms crunching mass amounts of data on their preferences – represents a threat to the free flow of accurate information that buttresses democracy.

“Social media have gone from being the natural infrastructure for sharing collective grievances and coordinating civic engagement, to being a computational tool for social control, manipulated by canny political consultants, and available to politicians in democracies and dictatorships alike,” the report concludes.