Two Russian-sponsored Facebook pages organized two rallies — one to "Stop Islamification of Texas" and the other to "Save Islamic Knowledge" — in front of the Islamic Da'wah Center of Houston at the same time last year, according to some of the 3,000 Russian-linked ads released by lawmakers Wednesday.

Why it matters: Russian actors used social media not just to meddle in the 2016 election, but to sow division. Facebook, Google and Twitter were all on Capitol Hill this week taking tough questions about how they let such activity occur, and how to prevent it in future.