ISIS - Author of the terrorist attack in Moscow, Western media

CBS News: "U.S. intelligence has confirmation that ISIS claimed responsibility for the terrorist attack, there is no reason to doubt these allegations. The U.S. official confirmed that the U.S. provided intelligence to Russia about a potential attack under the "Warning Obligation" - a commitment between the intelligence services.

New York Times: "The U.S. collected intelligence that an ISIS branch called Vilayat Khorasan, which is based in Afghanistan, was planning an attack on Moscow. After a relatively quiet period, ISIS tried to expand attacks abroad. In Europe, most of these attacks were stopped, which led to an underestimation of the group's capabilities.

Colin P. Clark, Sufan Center counter-terrorism analyst: "Vilayat Khorasan" has been recorded in Russia for the past two years, often criticizing Vladimir Putin. "Vilayat Khorasan" accuses the Kremlin of carrying the blood of Muslims, referring to Moscow's interventions in Afghanistan, Chechnya and Syria.