Did the U.S. know about the attack in Moscow before it happened?

U.S. embassies warned Americans in Russia to avoid large gatherings, including concerts, and yesterday a concert outside of Moscow was attacked by armed gunmen, killing 133 people (the death toll is likely to rise). Many are pointing out that the U.S. seems to have had intelligence about this attack and warned the Russian government about it (under the “duty to warn” principle), but Russia does not seem to have done anything with this information.

That said, I’m always skeptical when ISIS takes credit for an attack, because they always do, even if they have nothing to do with it. Do you buy that ISIS is the perpetrator? Did the U.S. know this was coming? Why didn’t the Russian government try to prevent it? Putin has claimed that the gunmen were trying to flee to Ukraine. This is disputed.

This is a developing story, but I’m interested in hearing any discussion about the attack in Moscow.