All eyes are on the horrific bombing of the Boston Marathon today. As far as we know, 2 people are dead and another 22 injured (and the numbers are likely to grow). We cannot be sure whether the blasts were acts of terrorism, but given there were two separate explosions and a third device found, it is pretty safe to say it was not an accident.
It is far too early to speculated on who is responsible for the bombing and why they chose to attack people running the historic event (many of whom are raising money for charities). But we can say one thing for sure: There can be no justification for the deliberate attack on innocent people.
Anyone with a vague understanding of international relations and history knows the US government does some very nasty things abroad that makes the country a prime target for terrorists looking to make a political point. You could conceivably argue that an attack on a US military base, or even an appropriate government building (say the CIA - an organization responsible for an extraordinary amount of violence and terror around the world) would be justified (although in my book, acts of violence are only justified when done in self defense), but this does not and cannot excuse acts of violence against people with absolutely no official stake in anything remotely political.
It is best we wait to uncover exactly what happened in Boston today, then look to the why. A rash response could reap even more chaos than the attack itself, as we saw after terrorists attacked America on 9/11. But make no mistake, there should be a response. The killers of innocents should never be allowed to get away with it.