A class guide
Gunmen Kill at Least 139 at Moscow Concert Hall, Russian Officials Say
U.S. officials said the Islamic State was responsible for the attack, one of the deadliest in Russia in decades.
U.S. Warned Russia Before Moscow Attack (msn.com)
Display of Battered Men Was Russia’s Warning to the Public, Analysts Say - The New York Times (nytimes.com)
Russian Media Intensifies Blame of Ukraine in Moscow Concert Hall Attack - The New York Times (nytimes.com)