Explained: Why did Isis-K attack a Moscow theater in Russia?

US confirms Islamic State's role in Moscow attack. Isis-K emerged in 2014, criticized Putin, and could target US interests. Group responsible for Kabul airport attack killing 13 US troops. Islamic State Khorasan (Isis-K), named after an old term for the region that included parts of Iran, Turkmenistan and Afghanistan, emerged in eastern Afghanistan in late 2014 and quickly established a reputation for extreme brutality.