According to The New York Times, U.S. officials revealed that U.S. Intelligence knew that ISIS-K was planning a terror attack on Moscow.

Update(1950ET): Although there has been much discussion and investigation around the early claims that ISIS claimed responsibility for the terror assault in Moscow, US government officials and media outlets are stating that the Islamic State's (or ISIS-K) statement is genuine. "A branch of the Islamic State claimed responsibility on Friday for the attac...