How is Russia likely to respond to the Moscow concert hall attack?

Following a deadly attack on a Moscow concert hall, with at least 137 killed, Russia has charged four men from Tajikistan. All appeared in court badly bruised with one falling in and out of consciousness. Daesh was quick to claim responsibility, but the Kremlin says Kiev was involved. So how is Russia likely to respond? Guests: Viacheslav Matuzov Former Russian Diplomat John E. Herbst Senior Director at Atlantic Council’s Eurasia Center Afzal Ashraf Senior UK Government Adviser