LONDON Syrian President Bashar al-Assad's days may be numbered but his fall could be slow and chaos could ensue.
Few analysts, foreign governments or intelligence agencies believe Assad himself faces any fate other than negotiated flight or death at the hands of his own people. But for Western officials, the challenge has become much more complex than forcing Assad out or pushing Russia to abandon him.
One senior Western government source said the most likely outcome might be protracted conflict such as that in 1980s Lebanon, dragging in foreign powers and lasting well over a decade.
Ultimately, much depends on Assad himself. But for all the efforts of Western intelligence services to build up a psychological profile, they say the actions of the British-trained ophthalmologist remain difficult to predict.
"In general terms, I don't think he is too hard to read: just another hood, albeit at the more sophisticated end of the spectrum... but gauging how he would respond to a particular conjunction of circumstances is all but impossible," says Nigel Inkster, a former deputy chief of Britain's Secret Intelligence Service MI6.
Foreign powers doubt Syria's troubles would end with Assad's removal. His Alawite minority might well fight on, if only to try to protect itself against the ethnic backlash that could follow his fall. The wider state - including the mainstream army left largely unused in favor of elite Alawite units - could collapse.
"We may see Balkanisation," says Anthony Skinner, head of the Middle East practice at UK-based consultancy Maplecroft. "Kurds in the north, Druze in the southern hills, Alawites in the coastal northwestern mountainous region and the Sunni majority elsewhere."
While Western officials quietly bemoan their lack of options, the choices available to the Syrian leadership are eroding even faster.
Some still believe Assad may want to put his family's safety first and broker some kind of escape. But there has been little sign of such appetite, suggesting the Syrian leader may have ruled that out.
"At this point, he's likely to fight... and may not even have any alternatives," said Ari Ratner, a former Obama administration State Department Middle East adviser and now a fellow at the Truman National Security Foundation.
"If he would have abdicated early in the crisis... perhaps he could have found safe harbor somewhere internationally as part of a negotiated settlement. But now he has so much blood on his hands... that would be nearly impossible."
While Damascus has been using attack helicopters against the rebels, it has held back from using fixed wing aircraft, perhaps wary of provoking the kind of internationally backed no-fly zone that led to foreign intervention in Libya.
There is a risk that in the dying days of his rule, Assad might unleash chemical weapons, feeling he has nothing further to lose. Potential targets could include states such as Turkey and Saudi Arabia that backed the rebels as well as Israel. Foreign intelligence agencies have also worried he might transfer chemical weapons to Hezbollah in Lebanon, giving them the capability to threaten Israel.
"The chemical weapons add another level of complexity to an already volatile situation," said Mona Yacoubian, a former State Department official and now a Middle East specialist at the Stimson Center in Washington DC.
"It is possible that feeling cornered... the Syrian government could act rashly - whether with chemical weapons or another tactic. However, it is also clear that this would be suicidal."
While Assad may fear intervention as seen in Libya or Iraq, foreign powers remain reluctant to take such a course. Sources with knowledge of the matter say some planning is underway, however, and some experts believe the possibility is growing.
Foreign support to the rebel Free Syrian Army - primarily arms, support and training from Saudi Arabia, Qatar and Turkey - is ramping up. But few analysts see such support as a game changer.
Western states remain largely on the sidelines, providing some intelligence and "non lethal" aid. Officials frequently bemoan the chaotic nature of the opposition and its limited capability to take on Assad.
With Assad backed by Shi'ite Iran and the majority Sunni opposition backed by predominantly Sunni-led Gulf monarchies, Syria is already exacerbating regional ethnic tensions.
"I fear Syria is sliding into a protected, sectarian civil war with the potential to wreak havoc across the region," says Stimpson Center's Yacoubian. "I do not think a negotiated solution or some type of managed transition is possible any longer."
(Reporting By Peter Apps; editing by Janet McBride)