"If there is a threat to the life and wellbeing of our employees...liquidate the bandits," the president said.
The Russian president's propaganda machine labels all dissidents as extremists, the state consolidates power in the name of security—and terrorism continues.
Three men have reportedly been detained, while the nine-storey building has been evacuated.
Engineering and psychology research can help improve evacuation procedures in subway attacks, like the recent St Petersburg bombing.
London and Berlin have also been criticized for not offering public gestures of solidarity, such as lighting up city monuments or raising the Russian flag.
Was Putin's presence linked to the timing and what history does the city have of extremism?