Western publics may have assumed that Islamic State was yesterday’s problem after the US and its allies smashed the group’s attempt to establish a caliphate in parts of Iraq and Syria. Now, the violently Islamist organization looks to be mutating into a pernicious new threat. Islamic State claimed responsibility for Friday’s assault on a concert hall in Moscow that killed at least 137 people, the deadliest attack in the Russian capital since 2002. Russian President Vladimir Putin dismissed a public warning issued by US officials who pointed to a branch known as ISIS-K, and he instead sought to divert public attention ... (full story)