Syria has risen to the top of the rankings of the most heinous regimes in the world. It has disregarded U.N.-Security Council mandates to end massacres of civilians, utilizing bloodthirsty militias and Iranian forces to augment its own readiness to besiege its cities and towns and shell them into submisson. All the international spokesmen seem to agree that Syrian dictator Bashar al-Assad must leave power, but there hasn't been a serious (syrious?) suggestion of how that was going to come about--until the past few weeks
The international community has had difficulty developing its response. U.N. Secretary-General Moon has taken a strong position against the depredations, but there has been considerable resistance from two nations in particular. Russia is a trading partner and patron of Syria, and both Russia and China take the view "on principle" against interference in the internal affairs of sovereign states, no matter how ugly they may be. Of course, the reason why they support the "sovereign right to kill our own civilians" (my term) is because they have exercised that right in living memory (Chechnya, Tienanmen) and may need to do so in the future. The only formula the intl.comm. has been able to develop so far--either in the Security Council, or in the nine-nation Moscow discussions--is one with proposals essentially calling for unilateral disarmament and surrender of power, not something that Assad's side, which knows that so far it is still winning the military conflict, is going to consider seriously. Instead the Assad spokesmen blame their massacres on rogue elements and international terrorists, in defiance of reports from eyewitnesses (which they do their best to forcibly eliminate, see Marie Colvin).
It's not going to be some kind of coalition of the western democracies either that will take action to remove "The Basher". A Libya-style no-fly zone assistance-at-a-distance approach is not even on the table, and, if it were, it wouldn't work. The rebel elements in Syria are brave, committed, but far from being armed enough, cohesive enough, or strategically powerful enough to combat directly against the Syrian military, which has so far held together, for a very good reason.
The top leaders of the Syrian regime are overwhelmingly from a small, Shiite group called the Alawites. They still pay some lip service to the principles of the Baath party--remember this name from Iraq and Saddam Hussein's reign of terror? Baath stands for unity, specifically pan-Arab unity, and helped propel Bashar's father, the equally brutal, even more devious, Hafez al-Assad, into power. The Assad family has promoted its own and sloughed off the non-Alawite elements, particularly the majority Sunnis, whom they have had no compunction about killing, on a very large scale if necessary, in order to keep power. (Somehow, the Baath concept of unity became "minority rule" in both Iraq and Syria, with the Sunni minority coming on top in the first and the Shiite minority in the latter.) So, the Alawites have a very good reason to stick together: if they fall, they can expect major reprisals, again, like Iraq, but in reverse. It's kill or be killed, as far as they are concerned. There have been defections, both at the high levels and, more frequently, among the predominantly Sunni conscripts, but the military has held together.
So, what has changed--what can change? A credible counterforce has emerged. Not Syria's neighbor Israel: much as they would love to take on Syria and thumb Iran in the eye, anything they would do would be counter-productive. It's Turkey; the Turks have a long border with Syria and not a particularly friendly one. During the decades-long Kurdish rebellion against Turkey, Syria was accused by the Turks of giving safe harbor to the rebels. Turnabout is fair play, and Turkey seems inclined to provide safety to Syrian refugees from the fighting, and it has clearly sided with the international community and with the rebels in calling for Assad's ouster.
Beyond that, there was a serious danger of escalation last week, when a Turkish fighter jet performing reconnaissance was shot down by Syrian surface-to-air arms. Whether the plane was in Syrian air space or not is an aspect upon which the two forces did not agree, but there was no doubt that the incident raised tensions and threatened to escalate to direct military confrontation.
That kind of danger would force Syria to step back--the Turkish military would likely be capable of defeating Syria's military on its own, and if the Syrians were to be foolish enough to take offensive action against Turkey, it could bring the full weight of NATO against it. Under the current circumstances, I could see an area being carved out at and around Syria's Turkish (northern) border which would remain beyond Damascus' power, and that could lead to progressive loss of control of the north and Assad's eventual defeat.