Thus validating the terrorists' approach. They use fear as a means of control and, according to your argument, it is an effective approach. I don't know what the answer is, but I do not think that allowing marauders to wander around the world staking claim to peoples' land is acceptable. Much less when they commit so many atrocities along the way.
If the choice is to: a) stop bombing and be hopeful that the terrorists will go away or b) try to stop the raping, murdering, and other atrocities via violence... I know where I stand.