With 70,000 Syrians Dead, Why are Chemical Weapons the Game Changer?

Back in August of 2012, President Obama established what he called a “red line” on action in Syria, which included the use of chemical weapons. At a press conference yesterday, Obama acknowledged that chemical weapons might have been used in Syria, although the nature of their use seems cloudy.
The President reiterated that the United States will not intervene in Syria unless there is clear evidence that chemical weapons have been used by the Assad regime. But, the President did affirm that the use of chemical weapons would be a game changer, although exactly what that means is unclear.
It could be argued that a red line has already been crossed. After all, 70,000 people have died in this conflict to date. Are we splitting hairs over the techniques used to kill people?
Shadi Hamid Director of Research at the Brookings Doha Center explores that question.