The problem lies not in condemning such acts of violence; the problem is in being a hypocrite. The very people who have condemned this act of violence may actually have felt happy within. Their thought processes being, "Good riddance; a few more 'Kafirs' have tasted the Wrath of God!"
Have you forgotten how scores of Muslims around the world were shown to be celebrating after 9/11 incidents? Can we blame them when their brains have been totally washed with N2I? Can we further blame them when the 'Powers of the World' go on oppressing them in the name of diplomacy?
To me, diplomacy is nothing but hypocrisy; however, the essential question is: Does Quran approve of diplomacy (as we know it today?)