To those of us who were watching closely, this is not much of a surprise. Via Buzzfeed:
Russian trolls posed as black activists on Tumblr and generated hundreds of thousands of interactions for content that ranged from calling Hillary Clinton a “monster” to supporting Bernie Sanders and decrying racial injustice and police violence in the US, according to new findings from researcher Jonathan Albright and BuzzFeed News.
While Facebook and Twitter continue to face intense public and congressional pressure over the activity from trolls working for the Russian Internet Research Agency, Tumblr has somehow managed to escape scrutiny. But the blogging platform was in fact home to a powerful, largely unrevealed network of Russian trolls focused on black issues and activism.
“The evidence we've collected shows a highly engaged and far-reaching Tumblr propaganda-op targeting mostly teenage and twenty-something African Americans. This appears to have been part of an ongoing campaign since early 2015,” said Albright, research director of the Tow Center for Digital Journalism at Columbia University.
[...] The Russian-run Tumblr accounts used the same, or very similar, usernames as the account names contained on a list of confirmed IRA accounts Twitter submitted to congressional investigators. In some cases, the Tumblr and Twitter account has the same profile image or linked to each other in their bios. Some IRA Tumblrs and Twitter accounts also cross-promoted content between platforms, further linking them together.
It's a compelling story, you should read it.