HCNN - Why Did ‘ISIS-K’ Target Packed Moscow's Concert Hall?

our men accused of attacking a Moscow concert hall that killed at least 137 people have been charged in Russia.

They all appeared to show signs of severe injuries, with one suspect seen bound in a wheelchair.

The four men were named as Mukhammadsobir Faizov, Shamsidin Fariduni, Dalerdzhon Mirzoyev and Saidakrami Rachabalizoda.

A branch of Islamic State (IS) claimed responsibility for the attack and released graphic footage of the gunmen firing inside the concert hall.

But questions remain over why the group would attack Russia and how the country will respond.