Quote Originally Posted by William F. Owen View Post
Terrorism is a police concern, the subject/object being the criminal use of violence, for political aims.
Insurgency is a military concerns, the subject/object being the military use of violence, for political aims.
Given this division of the subject matter (with which I agree BTW), the distinction becomes important when one deploys one's military forces to another country as part of an FID effort for example. It may very well be the case that this force gets called on to do CT work because the host nation does not have adequate police to do the job and one's own military is being (mis)used as police as a result.

I suspect one wants to be able to see the difference between CT and COIN as a way of trying to prevent mission creep or misuse of deployed forces. Within the US, it is somewhat easier (at present anyway) to keep the two distinct both because of laws about what our military is allowed to do or is prohibited from doing on US soil and because we don't have an active insurgency ongoing within our boundaries. Once one gets to Afghanistan, I think the distinction is much harder to discern.