[Phlyer]

Such policies save American lives because . . .

Maybe. In every "war" or war-like conflict in history, more 'troops' (including irregulars) have surrendered or just quit than were actually rendered ineffective through direct combat (casualties or captured). Working on the morale of the enemy - including convincing them that they're better off surrendering than continuing to fight - is very effective.

However, when the enemy chooses to disregard the rules of war - and gets away with it - things change. That encourages the next enemy to go even further to violate the 'rules' of war. And from that you get bodies burned and hung from a bridge, or heads hacked off with a knife.

Having enemies that feel they can get away with that and be treated in accordance with the Geneva convention if they are ever caught . . . that doesn't save American lives.

[ClayinVA]

The theory is called reprisal and it works pretty well. Tom Kratman explains it pretty well in a book called “a Desert called Peace”.