There probably isn't an answer, and if there is it changes from person to person. Some will say that a 100 Americans could die to save 50 and it was somehow "worth it". Others will say that it is never worth American blood to save a foreigner.
I do know we prefer to help far away, rather than close at home. Hungry Mexicans fleeing poverty, wanting nothing more than to pick your vegatables for $5.15 per hour, are a threat to our national security and should be stopped at all costs, yet spending billions of dollars and losing thousands of lives, is a small price to pay for Iraqi babies. I find it hard to cry for one and not the other. I wonder if Iraq was on our southern border, what we would do.
Whomever wins this and every election for President faces decisions that I cannot fathom.