LONDON (Reuters) - 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 Al Assad.
In a speech on Tuesday night, 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 internationalisation 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.
"Damascus is key - it's the place where you can cut the head off the snake," says David Hartwell, Middle East analyst at IHS Jane's. "The attack on the television station is obviously a new departure... but there have been attacks and uprisings in Damascus before that haven't led to anything. The question is whether they can continue it."
According to Syrian state media, opposition fighters stormed the compound of pro-government broadcaster Ikhbariya, located 20 km (15 miles) south of the capital, destroying a building and shooting dead three employees.
Tuesday also saw unprecedented levels of fighting elsewhere in Damascus suburbs including around the headquarters of the Republican Guard, although it appeared to ease again on Wednesday.
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.
"My sense is that the (Turkish jet) shootdown certainly escalates regional tensions and increases the possibility over the horizon for (longer term) military intervention," said Mona Yacoubian, a former US State Department official and now Middle East adviser at Washington DC think tank the Stimson Centre.
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.
The fact that a Turkish jet was blown from the sky with such apparent ease, experts warn, is a potent reminder of the risks.
Only the United States could inflict the kind of overwhelming assault on Syria's air defences 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 defences 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.
"It would be exceptionally difficult to establish a no-fly zone," said one Western military source on condition of anonymity as he was not authorised to speak on the topic to the press.
"Any form of 'safe haven' would demand high end war fighting capabilities and a very large ground force - almost certainly beyond the capabilities of any potential interveners given recent cuts in defence spending."
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.
While much of Gaddafi's military in Libya melted away in the early stages of the revolution, Syria's military is much more dominated by the Alawite minority and is seen likely to fight much harder including against any foreign forces.
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.
Without Assad, the Alawite minority in particular could find itself victim of revenge attacks following reported massacres in Sunni areas in recent weeks.
"The challenges surrounding Syria go well beyond Assad," says Aram Nerguizian, a visiting fellow and the Syria expert at Washington DC think tank the Centre For Strategic and International Studies.
"The post-colonial Syrian experiment is still coming undone... The long term socio-economic, political and sectarian challenges... could take years if not decades to play out."
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.
"I still don't think that Western powers will intervene," says Christopher Steinitz, Middle East analyst at the Centre for Naval Analysis outside Washington, part of the U.S. government-funded think tank CNA.
"No one will go it alone. Frankly, I think all parties at this point continue to see vague, covert support for the opposition as a winning strategy. There is no need for direct intervention."
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.
On Tuesday, Israeli-based website Debkha suggested British special forces had actually entered Syrian territory proper, presumably alongside rebel forces. For now, most experts remain sceptical - but the prospect may well be growing.
Weapons deliveries to the rebels are also believed to be growing. Most needed, analysts say, would be anti-tank weaponry and perhaps also anti-aircraft missiles - despite worries that they could ultimately fall into the wrong hands.
"It's never going to be officially acknowledged, but I wouldn't be surprised if the CIA and special forces types haven't been operating in Hatay for some time," said Hartwell at IHS Jane's. "I wouldn't have thought they will be operating across the border. But they will be training, coordinating and poring over satellite photos. And after last week, I think the Turks will be a lot less bothered about keeping that secret."
"Mission creep" could prove almost inevitable. If Syria's rebels can emulate their Libyan counterparts and actually seize large areas of territory, they may similarly call for direct air support to hold back Assad's forces.
Accidental or deliberate cross-border firing and growing talk of potential Syrian support for Kurdish PKK guerrillas could drive the Turks to launch at least occasional military strikes, regardless of the actions of Western and Gulf states.
By early next year, whoever occupies the White House - either a re-elected Barack Obama or Republican challenger Mitt Romney - could find himself pushed ever closer to a larger military mission. But that, some warned, could bring with it much larger geopolitical risks.
At worst, as it backs governments in Bahrain and Yemen while opposing them in Syria and Iran, some believe Washington could find itself trapped on one side in a regional confrontation between Sunni and Shi' ite.
"Looking head to a 2013, when Assad is still very likely in power, the prospects of a broader, international military conflict over Syria are looming larger," wrote Ian Bremmer, president of political risk consultancy Eurasia Group.
Reporting By Peter Apps; Editing by Peter Graff