Ian Bremmer's Quick Take:

A Quick Take to kick off your week. Lots we could be talking about. But I want to go to Russia, where we have had a major terrorist attack with over 130 Russian citizens gunned down, killed by terrorists.

The United States has warned the Russians both publicly so that American citizens would know about the concern, but also with actionable intelligence privately over the past couple of weeks that ISIS was planning an attack on an area with major crowds in Moscow. Putin publicly dismissing that, kind of wish he hadn't, but that we are where we are. And Putin has now spoken to the nation. There have been a number of gunmen that have been rounded up and arrested four, that we know of, Tajik citizens and Putin did not mention that ISIS has taken credit for this terrorist attack, nor that they then released videos of some of the attackers as they were engaging in terrorism inside the rock concert venue.

Instead, he spoke implausibly about links to Ukraine that don't actually exist. Why would ISIS-K do this? I mean, the main reason is because one of their two home bases, Syria and Iraq, in Syria, destroyed by Bashar al-Assad with the direct help from Putin and the Russian military. Nobody else doing that with Assad on the ground. And there have been many terrorist attempts against Russians as a consequence in that regard, but none with spectacular success for them like we've just witnessed.