Top Ten Reasons Romney Shouldn’t Arm Syrian Rebels
4. Syria is geopolitically too important to flood with powerful arms. It abuts Israel, Jordan, Iraq, and Turkey. A US-supplied war that spills over onto these countries is a nightmare for US policy.
5. The conflict between the Israelis and the Palestinians has entered a new and dangerous phase, with a significant expansion of Israeli theft of land and resources from Palestinians of the West Bank. The latter had been convinced to lay down their arms and join in a peace process. The combination of the betrayal of all the promises made to the Palestinians about giving them a state and returning to them their territory, along with easy availability of US arms from Syria, might well provoke another violent Intifida or uprising.
6. The conflict in Syria is already threatening to destabilize Lebanon. That countrys disarming of its sectarian militias in the 1990s after the Taif Accords was a major achievement for stability in the Eastern Mediterranean. American arms given to Syrian rebels would risk reviving armed militias in Lebanon, where some groups (the Shiite Hizbullah e.g.) favor the al-Assad regime whereas others (many Sunnis) support the Syrian opposition. There have already been clashes between Allawis and Sunnis in the northern city of Tripoli.
http://www.juancole.com/2012/06/top-ten-reasons-romney-shouldnt-arm-syrian-rebels.html
Perhaps, that is why the US is not arming the Syrian rebels.