Russia-purchased ads on Facebook during the 2016 election were aimed at stoking social tensions

Some of the suspicious Facebook ads purchased by Russian agents ahead of the 2016 presidential election were aimed at influencing its outcome by preying on racial, religious and other social tensions in the United States, according to two sources familiar with the matter.

At times, these Kremlin-sourced ads even played on both sides of an issue — advancing and opposing causes including Black Lives Matter and gun control, for example — in a bid to stir potential political unrest, said the sources, confirming a report by the Washington Post on Monday.

The suspect ads comprise a small slice of the roughly 3,000 ads that have become the subject of increasing scrutiny by the U.S. Congress as well as former FBI Director Robert Mueller, who is leading the U.S. government’s official probe into Russian interference during the 2016 election.

Facebook hinted at some of the ads’ content in a blog post earlier this month, saying, “the ads and accounts appeared to focus on amplifying divisive social and political messages across the ideological spectrum — touching on topics from LGBT matters to race issues to immigration to gun rights.”

The new — if meager — details about Russia’s approach to playing both sides of divisive issues are guaranteed to keep Facebook in the political hot seat, all at a time when the company is facing criticism for allowing political advertisers and others to target users based on sensitive demographic information, such as race or religion.

A spokesman for Facebook declined comment. Spokespeople for the House and Senate committees investigating the matter did not immediately respond to requests seeking comment.

Speaking on CBS’s “Face the Nation” over the weekend, Rep. Adam Schiff, the top Democrat on the House Intelligence Committee, acknowledged the ads’ tone: He said they were “designed not only to help Donald Trump or hurt Hillary Clinton, but more fundamentally, to divide Americans, to pit one American against another on some very divisive issues.”

So far, Facebook has provided the full tranche of Russia-tied ads only to Mueller. It has not yet shared all 3,000 with investigators on the House and Senate Intelligence Committees, according to two sources, though it promised to do so last week. The company also announced a number of major changes to its advertising platform, including new transparency requirements.

Nor is it the only tech company facing scrutiny in the nation’s capital. This week, lawmakers investigating Russia’s alleged election meddling plan to grill another tech giant — Twitter — over the spread of misinformation on its own platform. The company will brief the House Intelligence Committee, a source confirmed, in addition to its Senate counterpart, a meeting first reported last week.

This article originally appeared on Recode.net.