(CNN) On May 21 2016, a handful of people turned out to protest the opening of a library at an Islamic Center in Houston, Texas. Two held up a banner proclaiming #WhiteLivesMatter. A counter-protest began across the street; video shows a noisy but non-violent confrontation.

The rally -- called "Stop Islamization of Texas" -- was called and promoted by a Facebook page called Heart of Texas, which had wrongly alleged that the Islamic library had received public funding. But the Heart of Texas page listed no contacts in the Lone Star state. In fact, it was operated by a "Troll Factory" called the Internet Research Agency thousands of miles away in St Petersburg Russia, CNN has learned.

One of the people who attended the rally later complained: "Heart of Texas promoted this event but we didn't see ONE of them."

The Houston rally sheds light on an effort originating in Russia to sow discord in the U.S. through social media; in this case it had real impact on the ground.

Not only were police on the scene, the executive director of the Council on American-Islamic Relations in Texas, Mustafaa Carroll, told CNN that his organization had contacted the FBI about comments posted on the Heart of Texas page before the protest. One of them read: "Need to blow this place up. We don't need this shit in Texas."

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