The bomb attack on Wednesday that killed Syria's defence minister, Dawoud Rajha, and more importantly his powerful deputy, Assef Shawkat, brother-in-law to President Bashar Al Assad, underscores that we are in a radically new phase of the Syrian conflict.
This was indirectly affirmed last weekend, when the International Committee of the Red Cross declared the situation in Syria to be a "non-international armed conflict" - in other words, a civil war. This the ICRC did to ensure that combatants would respect international humanitarian law.
However, definitions mean a great deal, especially when the Syrian opposition prefers to define its struggle as one directed against a homicidal regime bent on retaining power.
Even emancipative crusades can still qualify as civil war, or a stage of civil war, when the enemy principally includes one's countrymen, and when fighting becomes institutionalised and rationalised. Rather than tussle over words, it may be better to accept the reality of civil conflict in order to neutralise its worst manifestations.
Where those unhappy with the civil war appellation may have a point is in arguing that events in Syria have taken on the characteristics of a proxy war. Some describe it as an Iranian-Saudi confrontation; others as a battle between Russia and the West; yet others as a complex array of conflicts fuelled by outsiders.
Perhaps, but without Syrians firing on Syrians there would be no hostilities. Many civil wars transform themselves into proxy wars.
It's not surprising that the ICRC can now identify Syria as a country in civil war, given the breakdown of efforts to resolve the crisis. Diplomats are the most resistant to adopting terms such as "civil war", because it limits their options. The plan of the United Nations-Arab League envoy, Kofi Annan, is a dead letter, despite Mr Annan's efforts to find common ground between the western countries on the one side, and Russia, China and Iran on the other.
Mr Annan's failure derives precisely from the fact that the former UN secretary general underestimated domestic Syrian animosities in the initial formulation of his peace plan. By calling for negotiations between the regime of President Assad and the opposition - even though Mr Al Assad's forces had by then killed between 10,000 and 15,000 people - Mr Annan ignored the deep gulf in Syrian society.
It is easy, and perhaps unfair, to blame Mr Annan for dynamics that have largely remained outside his control. When he arrived, his task was to engage with all sides. This was never made easy by the significantly different aims of his official sponsors - the Arab League, which was looking for a transition away from Mr Al Assad, and the United Nations, where there was no consensus over such an outcome.
But Mr Annan has also found himself too much a believer in, and a prisoner of, the negotiating process. When those in Syria's opposition cast doubt on whether they are in a civil war, they should admit that it was their understandable and laudable refusal to reconcile themselves with Mr Al Assad, or to give him leeway to survive politically, that made them dismiss Mr Annan's project. To say no to a mass murderer, even if civil conflict ensues, is not always reprehensible.
Fortunately or unfortunately, the direction of events in Syria will be determined by the Syrians themselves, not foreigners. The spread of fighting to Damascus in the past days was never in doubt. For months the regime had been losing support in the capital, particularly among the Sunni-dominated merchant class, which had so decisively swung behind Hafez Al Assad during the early 1980s when he was in a showdown with the Muslim Brotherhood.
While the armed opposition is still incapable of taking control of Damascus, its ability to seize the initiative at the very centre of the regime's power base, after months of savage military assaults by Mr Al Assad's units, indicates that the tide is turning. Yesterday's suicide bombing in the heart of the capital underscores this trend. Those vital intangibles in winning wars - will, persistence, confidence - have shifted decisively to the president's enemies.
Eventually, this will trigger a collapse in the will, persistence and confidence of Mr Al Assad's followers, who may have no choice but to contemplate retreating to Alawite areas in north-western Syria. If that happens, Syria could possibly enter into a more devastating phase of its conflict.
To assume a rapid endgame once Mr Al Assad flees Damascus may be simplistic. Centrifugal forces have been unleashed, and if the Alawites decide to go one way we should expect the Kurds in north-east Syria to go a way of their own. This could undercut the emergence of a unitary Syria and even lead to ethnic cleansing in districts where communities live side by side. The only way to avert such a nightmare scenario is to begin working now to try reconciling the different religious and ethnic groups.
That is why recognising the civil component of the ongoing war is crucial. If it's merely about ousting Mr Al Assad, then the opposition could one day be surprised to find itself triumphant but also ruling over a fragmented Syria where communities mistrust one another - and specifically where the Sunni majority is feared by minorities.
The Lebanese are still paying for their inability to accept that they were caught up in a civil war. Post-war reconciliation was never regarded as important enough to be made even a secondary priority. That is why the society is riven with doubt today, lacking in cohesion. Syrians should avoid that mistake, and they still have time to do so.
Michael Young is opinion editor of The Daily Star newspaper in Beirut
On Twitter: @BeirutCalling