"Afghan Officials Deny Reports Of Soldiers Beheading Prisoners," by David Rhode, New York Times, 24 June, p. A12.
"Assessing a Gruesome Toll After a Rash of Beheadings: A terrorist act called the ultimate symbol of power over an enemy," by Daniel J. Wakin, NYT, 24 June, p. A12.
You have an insurgency, and there's no way you're going to expel the highly superior military occupational force. So don't try to fight them, just go after individual civilians from the same country and cut off their heads, broadcasting your murders on the Internet. Pretend to yourself that this act gives you "ultimate power over your enemy." Wage your war of perversity for all it is worth. Tell the people that to cooperate with outsiders is death. Get them so afraid to interact with the outside world that they have no choice but to submit to your rule. Then turn your country into an dictator's paradise where women have to do whatever they're told, kids only get the education you deem they're worth to receive, and you and your elite cronies get to control all the wealth-generating natural resources.
It's a plan, baby. One that's certain to work against a flaccid, degenerate West that runs at the first sight of blood.
On the other hand, if you're trying to establish a legitimate government authority that actually encourages growing mass connectivity with the outside world, then you're careful not to engage in similar behavior, because you certainly don't want to be associated with that sort of brutality. Bad for business, bad for investment, bad for the soul.