With a high profile attack on a government TV station, escalating fighting around Damascus and talk of increasing covert foreign support, Syria's rebels are bringing the fight ever closer to Bashar Assad.
Assad said the country was now “at war” and that all sectors of the government and country must devote their energies to the war effort. A string of recent military defections suggest even some of his supporters may have had enough, but most analysts and foreign officials believe his government could cling on well into 2013.
With the shooting down of a Turkish reconnaissance jet on Friday the latest sign of the creeping internationalization of the conflict, there are growing signs outside powers may be dragged in ever deeper whether they want to or not.
For now, few believe there is any imminent prospect of the kind of foreign military intervention seen last year to oust Libya's leader Muammar Gaddafi. But one lesson from last year almost certainly does carry across, analysts say: that the true endgame, if it comes, will be in the capital.
In Libya, opposition fighters with smuggled and parachuted weapons and supported by Arab and Western special forces advisers swept into Tripoli often unchallenged. Such scenes in Syria, however, could still be a relatively long way away.
In principle, world powers remain committed to the diplomacy of former United Nations Secretary General Kofi Annan. But some diplomats believe international talks on Syria scheduled for this weekend in Geneva may not even take place, so great are the divisions.
Despite western hopes that Russia might be persuaded to abandon long-time ally Assad, Moscow appears determined to back him, making it clear it intended to ensure delivery of several attack helicopters despite widespread condemnation.
At the same time, having initially held back, Western states and particularly Arab nations appear to be stepping up support for the rebels.
Turkey is allowing the Free Syrian Army safe haven within its territory. Following the jet incident it may well be willing to increase its own support and allow nations to do the same.
Earlier this month, British Foreign Secretary William Hague said rather than looking for a Libya-style campaign, foreign powers should see Syria as more akin to 1990s Bosnia.
That, some including foreign office officials believe, was aimed at suggesting that regardless of intent, other states including Britain might ultimately be forced to become militarily engaged.
But a serious intervention could require tens of thousands of troops, comparable to the 2003 U.S. invasion of Iraq. With Western states in particular exhausted by recent wars and economic woes, enthusiasm is limited.
Only the United States could inflict the kind of overwhelming assault on Syria's air defenses necessary to open the door for broader action. That could require two aircraft carriers and likely dozens or more other aircraft from Turkish, Cypriot and other bases, military sources say.
Syria's air defenses are far more powerful than the those of Gaddafi's Libya last year or Saddam Hussein's Iraq in 2003. U.S. air forces have not taken on such a task at least since Kosovo in 1999.
The bulk of any ground force entering Syria would almost certainly have to come from Turkey - and that is a prospect that officials in Ankara are seen very keen to avoid.
If Assad were to fall or flee abroad, some analysts believe the country would simply collapse further into chaos. Foreign states could then be confronted not just by the danger of Al Qaeda-linked militants moving in but also the prospect of even more ethnic violence.
Despite such longer-term worries, however, there are growing signs that the West and Arab states have decided that helping push the FSA towards victory may be the only option.
Although official confirmation is inevitably absent, there has been growing talk of foreign special forces - particularly British, but perhaps also US, Qatari, French and others — operating in Turkey's border Hatay province.

n Peter Apps is a political risk reporter for Reuters.
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