Ask them again what we SHOULD do. If any of their answers indicate that they would rather American servicemen die than Afghani civilians (because they're volunteers, you know) remark rather thoughtfully, "oh, yes, that's right... lots of inner-city blacks and rural whites who can't afford college and can't find a job end up volunteering in the military."
If you make it look as though they are sacrificing inner-city blacks (for ANY reason) they are going to have a liberal reaction that's bound to be fun to watch. (-:
Ohhhhhh yes! Good one! Just like putting baking soda and vinegar into an empty film vial!