The meme-laden Tumblr platform is the latest social media and blogging outlet to be unmasked as a distribution channel for Russian agents to rip at America’s societal fault lines and seek to influence citizens’ voting habits, according to a report by BuzzFeed News.

Facebook and Twitter have been firmly in the spotlight on this issue since the shock result of the 2016 US presidential election. Google has also self-reported on Russian disinformation on its platforms. But the role of other social platforms in spreading Kremlin propaganda has faced less scrutiny thus far.

BuzzFeed worked with researcher, Jonathan Albright, from the Tow Center for Digital Journalism at Columbia University, to identify Russian-backed account activity on Tumblr. It says the analysis reveals “a powerful, largely unrevealed network of Russian trolls focused on black issues and activism” which dates back to early 2015.

Some of the Russian-linked blogging activity on Tumblr was apparently aimed at boosting support for Bernie Sanders at the expense of eventual Democratic candidate nominee Hillary Clinton. The Democratic nominee process concluded in July 2016. While the US presidential election itself was held on November 8, 2016.

“The evidence we’ve collected shows a highly engaged and far-reaching Tumblr propaganda-op targeting mostly teenage and twenty-something African Americans,” Albright is quoted as saying.

“This appears to have been part of an ongoing campaign since early 2015,” he added.

We’ve reached out to Tumblr owner Oath‘s press office with questions about the research — at the time of writing the company has not replied. (For the record Tumblr owner Oath is also TechCrunch’s parent company.)

Oath did not respond to BuzzFeed’s requests for comment on its research.

The methodology used for unmasking Russian agents on Tumblr appears to be a pretty simple one: The researchers cross-referenced Tumblr accounts that used “the same, or very similar” usernames from a list of known Internet Research Agency (IRA) accounts, previously submitted by Twitter to congressional investigators. (The IRA being one of the confirmed Russian trollfarms; others are also known to exist.)

Incidentally, last month Twitter updated this Russian bot list — saying it had now identified an additional 13k Russian-linked bots that had made election-related tweets, pushing the total number to more than 50,000. (Of those it said about 3,800 were linked to the IRA.)

In January Twitter also said it now thought that 1.4M people had engaged with Russian trolls during the US election.

It’s not yet clear how impactful Kremlin agents’ Tumblr dis-ops were. But the most successful of the Russian-linked Tumblr accounts identified by BuzzFeed’s analysis had apparently created multiple posts generating hundreds of thousands of “notes” on Tumblr (aka totaled likes, reblogs, replies etc).

The research also found Russian-linked Tumblr accounts cross-posting content from other social platforms — including Twitter and Instagram.

BuzzFeed says most of the accounts it linked to the IRA are no longer active on Tumblr, although it specifies that two are still sharing content on the platform (though it describes the content as “completely unrelated”, and speculates it’s possible that account ownership has since changed).

In terms of the types of socially divisive content being shared via these Russian-linked Tumblrs, BuzzFeed cites examples that sought to link Clinton to a former KKK leader; complained about unfair media coverage of a Sanders rally; and decried racial injustice and police violence in the US.

After Clinton won the Democratic nomination, some of the Russian-linked Tumblrs that had been backing Sanders apparently started pushing pro-Trump content.

The research also unearthed a network of links out from Tumblr to “thousands of still-remaining Twitter posts, black culture blogs, at least several hundred still-remaining Facebook posts, sign-ups for online petitions, and a number of Reddit threads related to pro-Bernie news, Hillary conspiracies, and in-classroom racial matters”, according to Albright.

Given the cross-referencing method that was used to ID Russian activity it’s entirely possible other Kremlin-backed Tumblr accounts existed on the platform (and/or still exist) — but which have yet to be identified.