Israel is reportedly weighing military action in Syria to counter scenarios regarding Syrian chemical weapons, even at the cost of a regional war. There have been reports that chemical weapons have been used recently in President Bashar Al-Assad's battles with opposition forces.
The first of the three main scenarios is that the chemical weapons will fall into the hands of the rebels, which would dramaticly undermine stability in the north, since it is unknown if and how they would use it against Israel. Secondly, Assad might use the weapons against Israel as a final gesture or a last-ditch shot at "the common enemy", given the opposition's claim that it will remain hostile to Israel. The third scenario sees Assad as passing the weapons to Hizbullah terrorists in Lebanon, which Israel would also view as crossing a red line.