It was unknown whether the mortar shells were fired by Syrian government forces or rebels fighting to topple the government of President Bashar al-Assad. The Turkish response seemed to assume that the Syrian government was responsible.
An alternative is for diplomatic efforts to focus first on how to end the violence and how to gain humanitarian access, as is being done under Annan’s leadership. This may lead to the creation of safe-havens and humanitarian corridors, which would have to be backed by limited military power. This would, of course, fall short of U.S. goals for Syria and could preserve Asad in power. From that starting point, however, it is possible that a broad coalition with the appropriate international mandate could add further coercive action to its efforts. -page 4, Assessing Options for Regime Change, Brookings Institution.
In addition, Israel’s intelligence services have a strong knowledge of Syria, as well as assets within the Syrian regime that could be used to subvert the regime’s power base and press for Asad’s removal. Israel could posture forces on or near the Golan Heights and, in so doing, might divert regime forces from suppressing the opposition. This posture may conjure fears in the Asad regime of a multi-front war, particularly if Turkey is willing to do the same on its border and if the Syrian opposition is being fed a steady diet of arms and training. Such a mobilization could perhaps persuade Syria’s military leadership to oust Asad in order to preserve itself. Advocates argue this additional pressure could tip the balance against Asad inside Syria, if other forces were aligned properly. - page 6, Assessing Options for Regime Change, Brookings Institution.
Because creating a unified national opposition is a long-term project that will probably never fully succeed, the contact group, while not abandoning this effort, may seek more realistic goals. For example, it might concentrate maximum effort on breaking Asad’s hold on, say, the elite of Aleppo, which is the commercial capital and which is also the city where Turkey has the greatest leverage. If Aleppo were to fall to the opposition, the demoralizing effect on the regime would be considerable.
Should this option fail, the United States can simply accept a bad situation in Syria or escalate to one of the military options below. - page 6, Assessing Options for Regime Change, Brookings Institution.