They can be violent acts but I doubt they are senseless. There are people who make politics and/or business this way. This is cruel, granted, this is inhuman, but somebody has paid quite an amount of money for this monstrosity to take place. People like that, despite what others may think of them, seldom do anything without expecting some political or economical dividends from that. Terrorism is a reality of modern society. This could have happenned at any time, at any place. I doubt there's a cure against this disease. It's a constant risk everyone should accept.
@Sgt. Cold
Are you so sure that those who did it were muslims? No, I'm not speaking about the brainless pawns who put explosives on and connect the wires. I'm speaking about those who make the decisions? Are you so absolutely sure? Well, I'm not.
Look, people, just some facts that could have no connection whatsoever.
1. There was nationalistic turmoil on Manezh square in December. Well, nothing breath-taking, but Putin DID meet the footbal fans leaders later and tried to talk sense to them (he'd never done anything like that with any other manifestants).
2. Security measures against immigrants were strengthened
3. Now this explosion.
What feelings will it stir in common population (especially after they told on TV that this was done by the 'Caucassian underground')? Fear? No. We risk every day and the risk of getting into a car accident is much greater than the risk of being exploded... still. But hate? Yes. Hate.
It appears that there are people in Russia who want to stir as much national antagonism in Russia as possible. And I doubt they can be possibly muslims.