Saluting with misty eyes
Quite honestly, this is an extremely unfair question, and is one that not a person on this planet can honestly answer anything other than, "I don't know".
This, in my opinion, falls into the category of you don't know untill you are there. Anyone can say that once the bullets are flying, they would be a junior Rambo. Anyone can tell you that if someone killed their wife/husband/kids/dog/big screen tv they would return in kind. Anyone can feel that if they were caught in the middle of a hijacking, that they would say, "Let's rool" and subdue the culprits... yet, no one knows what they would do until they are put into that exact situation, and were forced to make a- possible- deadly decision.
Right now, this very moment, you are asked to blow up a dam that will flood out a valley and kill in excess of 5,000 enemy soldiers that would normally kill numerous of your fellow contrymen... fairly easy decision. Now, place those same enemy combatants into a valley with 10,000 non-combatants who have done nothing to you, and who want nothing more out of life than to fill their ricebowl for the next day. Do you blow up the dam or not? You can save 100,000 American lives by killing 50,000 people whom you have no animosity for, and who have done nothing to you, and whom you don't even know, and who have not killed a single American warrior (or civilian), and whose only desire is to make it through another day of their meger life and raise their families... What do you do?
The only proper answer is, "I have no clue at all."
What would you attempt to do...if you knew you could not fail?.