Irregular warfare is a nightmare. It is underhanded, vicious, cruel, thankless and interminable. Like the undead or those characters in sci-fi films that reconstitute themselves after being blown apart, the enemy keeps coming back for more. Not the same guys, but their brothers, sisters, fathers, alienated immigrant cousins, distant clan members and ideological bedfellows. The pretty girl bats her eyes at the young soldier while her brothers plant improvised explosive devices (IEDs) so when he returns home, his missing leg will always remind him of her welcome. Not surprisingly, it is not a form of warfare that most regular soldiers and sailors want to fight. Unfortunately, our adversaries do.

http://www.armedforcesjournal.com/2007/04/2559226