The President made the statement that Syria's use of chemical weapons would be a game-changer. Let's revisit the Just War tradition to see if we can find out why that is so.
Chemical and biological weapons are considered anathema in the JW tradition not because they are sui generis or because of their destructive power. They are condemned because of their indiscriminate nature. You can't aim a chemical weapon. You have no way to insure a biological weapon targets only the military. In the JW tradition, the principle that is invoked in this is non-combatant immunity.
Non-combatant immunity, in my option, is the single most important facet of the Just War tradition. Civilians should be off limits in overt conflict. THIS is the heart of the issue in Syria.
Instead of invoking chemical weapons as a game changer, the President should have invoked the violation of non-combatant immunity as a game changer. This is, after all, why chemical weapons are so horrible.
The Assad regime violated non-combatant immunity a long time ago. The President should have already acted.