What if the country that was using chemical weapons against its own people happened to be an ally of the U.S.? Would we still use missiles against them? Assad gets away with killing his own people via chemical weapons and the world does nothing. What happens when the next dictator decides to use an even stronger chemical weapon to achieve the same end? Chemicals don't exactly understand international borders; what happens if a chemical weapon - oops! - drifts over a border and kills people from a different country? Where does it end?