I read on a milblog a while back a testimonial from a marine during the final battle to clear Falluja that there was an understood fact that no marine/soldier would allow themselves to be taken alive considering what the "insurgents" were doing to their captives...and the field day the media would have if the terrorists held US pow's and brandished them on the internet...etc...it was a very sober account of how every US military person in a combat zone would fight to the death...because the US is not fighting any type of civilized adversary...we're fighting rabid, cracked up, dogs in Iraq and Afgahnistan and around the world.
I agree, and there's only one thing you can do with a mad dog...you put it down! No mercy for these animals.