For most of the past 18 months, it has appeared that the uprising against President Bashar al-Assad in Syria stood only a limited chance of success.
There was little prospect of Western military intervention, as occurred in Libya, or even meaningful international sanctions because the ruling regime was shielded by Russia.
As well, President Assad displayed no scruples in sending in helicopter gunships, artillery and militia to attempt to suppress rebel strongholds.
But in quick time, a dramatic change has taken place - so much so that the Assad regime must recognise its time is coming to an end.
The most obvious manifestation of this shift in the balance of the conflict is the fierce clashes in the streets of Damascus and the bombing of the national security headquarters while a high-level meeting was in progress.
Previously, the capital has been largely immune to the fighting, presenting an image of calm to the outside world.
Then there is the escalating number of defections of senior regime figures. They strengthen an insurgency that must now sense victory and see little purpose in any ceasefire negotiations.
This change in fortune is a result of several factors. President Assad's failure to strike a knockout blow - partly because the opposition has been dispersed across Syria - has emboldened the rebels, as have supplies of arms from Saudi Arabia, Qatar and others.
At the same time, Russia has said it will conclude no new arms deals with Syria. Thus, while Moscow has continued to back the Assad regime as an ally of long standing, that support has become less relevant than it was previously.
The most likely scenario now is that the rebels, under the flimsy political umbrella of the Syrian Support Group, will claim power through victory on the battlefield. This has become a mass uprising, as evidenced by the Red Cross declaration of a civil war.
And despite all the Western anguish over the failure to intervene when several horrendous massacres by the regime were revealed, that may be the most appropriate outcome. Military intervention may well have placed the West in a quagmire similar to that from which it has just extricated itself in Iraq.
President Assad's regime is dominated by his fellow Alawites (a Shia group) and Syrian Christians. Their opponents are largely Sunni, whose desire for vengeance runs deep.
The enforced departure of President Assad will not settle their differences. There can be no guarantee that a replacement administration would be any less oppressive, or that Syria would be any more stable, or that the turmoil would not spill outside its borders.
This points the way forward for the international community. There is little to be gained from United Nations resolutions urging a ceasefire or imposing stiffer sanctions against the Assad regime. The tide of civil war has swept past that point.
The focus should be twofold. First, the UN mission headed by former Secretary-General Kofi Annan must convince President Assad that it is time for him to go. Second, there must be strenuous efforts to achieve a reconciliation between Sunni and Shia to avoid the sort of bloodshed that enveloped Iraq. As a first step, the Syrian Support Group must be strongly encouraged to offer guarantees of safety to the country's Alawites and other minorities.
As with other despots unseated during the Arab Spring, no tears will be shed for Bashar al-Assad. Neither his brutality nor the lack of direct Western support for the rebels will save him. But as developments in Egypt, Tunisia and Libya have proved, nothing can be taken for granted after uprisings. A post-Assad Syria will pose particularly complex challenges.