Russia says it’s hard to believe Islamic State could have launched Moscow attack ReutersMoscow concert attack: fear death toll higher after reports of up to 100 missing The GuardianVladimir Putin blames ISIS and Ukraine for Moscow concert attack USA TODAYAnalysis | Putin sees Kyiv in Moscow terrorist attack. But ISIS is its own story. The Washington PostRussia Has No Formal Death Penalty. Here’s How That Might Change. The New York Times