War on concepts
This is properly called a War on Terrorism because what we are fighting is the concept that the murder of civilians is a legitmate military-political instrument - and wherever this concept is sustained, there is where we must fight.
Mmm ... endless war ...
UPDATE: Brian Leiter addressed this issue way back when:
...couldn't we have an agreement, at least among grown-ups, to stop using the phrase "war on terrorism," unless we have an explicit understanding that it is not a real war, but rather is like the "war on drugs," i.e., a metaphorical war that will fail, and so one that doesn't excuse any hair-brained schemes cooked up by beady-eyed, morally stunted politicians. One can't wage war on a political technique. Full stop. One could wage war on a group, perhaps, or on a country (as the US has been doing), but you can't wage war on techniques that can be employed by anybody for any purpose. The US waged war on Afghanistan, and is waging war on Iraq, and is engaged in an international manhunt for members of a terrorist group, but there is no such thing as a "war on terrorism." It doesn't exist. Look in the mirror and repeat that.