[Lurker]

The Russians warned us about the Tsaernev brothers and we did nothing with the information.

L

[Navy Patriot]

The Russians warned us about the Tsarnaev brothers and we did nothing with the information.

Yes, that is correct, and there are some additional facts about the timeline that show Russian Good Faith.

The Russian government warned U.S. authorities that Boston Marathon bomber Tamerlan Tsarnaev was a violent radical Islamist more than a year and a half before the April 2013 bombing, but American authorities missed multiple chances to detain Tsarnaev when he was traveling to and from Dagestan for terror training.

The early (and non public) warning (by the FSB) indicates earnest anti terrorist cooperation by Russia without ulterior motives, as the time allowed full investigation by the FBI and the discovery of who financed and directed the Tsarnaev Brothers.

As you said, the FBI did nothing.