PARIS: A fight to the death to keep Damascus, a fall back to his Alawite strongholds or even exile abroad - experts say Syrian President Bashar Assad must be considering a range of choices in the face of an armed rebellion.

And each, they say, is fraught with risks.

For now the embattled leader's focus is on retaining control of the capital, where Syrian forces launched an all-out assault on opposition strongholds on Friday two days after a bomb attack killed four senior members of the regime.

"As long as Assad controls the capital, he controls the government and has legitimate power," said Fabrice Balanche, an analyst with the Mediterranean and Middle East Studies and Research Group in Paris.

"The redeployment of troops from the Golan and the Iraqi border to the capital, at the risk of stripping other fronts, shows that he is going to stay," Balanche said.

"There is a scorched earth dimension in Damascus," said a source with close knowledge of the regime, adding that the idea seemed to be to hold on to areas almost to the bitter end and "fall back if you don't succeed".

If Damascus was lost, experts believe there are plans for Assad to seek refuge among his minority Alawite ethnic group in the northeastern mountains of the country.

Regime opponents have for months contended that Assad and his allies have been stockpiling arms, including heavy weapons, in the area.

"It is very likely that he will embark on a desperate battle from this redoubt," said Joseph Bahout, a Middle East analyst at the Paris-based Institute for Political Studies.

"The defence could last for months," he said, adding that the conflict could then take on an ethnic dimension, as a battle between Alawites and the country's Sunni majority.

"(Assad) is perhaps hoping that this will entail an international response to put an end to the conflict with a partition" that would allow Assad's regime to survive in some form, Bahout said.

But as the region is a mixed one that is home not only to Alawites, this option could lead to an especially bloody civil conflict, experts said.

"This region will fiercely defend its territory. To create a redoubt would require uniformity and there are fears of ethnic cleansing," said Thomas Pierret, a Syria expert at the University of Edinburgh.

Several experts said there was also a chance that the Alawites would decide Assad was doing more harm than good and turn against him.

"Ultimately he could be rejected by the Alawites as someone who failed to protect the community and may be sacrificed," Balanche said.

As for a Yemen-style regime-led transition that would see Assad leave power in exchange for immunity, experts said that option was becoming less likely by the day.

"I don't think a regime-led transition is possible in Syria given the blood that has been shed and the battles we are going to see. This regime is not going to give up easily, trust me," said Salman Shaikh, a Syria expert at the Brookings Doha Centre.

That leaves potential exile as an option, with countries including Russia, Iran and Belarus often mentioned as possible destinations.

The source with close knowledge of the regime said Assad could escape by boat from Tartus or by plane from Damascus.

But that might not resolve the crisis, the source said, and could leave behind powerful regime figures who would be "tempted to go even further with the horror".