Bashar Assad is in a box from which he cannot escape, western diplomats say, after UN investigators implicated senior regime figures in February's murder of the Lebanese politician, Rafik Hariri. But while Syria's president is no Houdini, rumours of his imminent political demise appear exaggerated.

One reason is international divisions about what to do. The US and Britain want swift UN action, leading to possible sanctions. But France's foreign minister, Philippe Douste-Blazy, said yesterday that any decision-making should be left until the UN inquiry was complete.

Damascus has credible grounds for hoping that Russia and China will oppose western-initiated punitive action through the UN, as has been the case with other "states of concern" such as Sudan, Burma and Zimbabwe.

And Washington may yet be distracted by a bigger target. Stephen Hadley, the US national security adviser, was in Moscow yesterday seeking Russian support for UN action against Iran. The Syrian dossier barely got a mention.

"I expect the UN security council will only issue a warning this week," said Rime Allaf, a Syria expert at the thinktank Chatham House. "But if the UN inquiry's final report on December 15 says regime figures should be handed over, Assad will be in a very difficult position."

Syria's leader has other options. He would play for time and to the Arab gallery, Ms Allaf suggested, presenting his country to the Muslim world as the latest victim of a familiar American antipathy. That is already happening. Syria rejected the UN report as politically motivated; at the same time, the foreign ministry dangled the possibility of increased cooperation.

And the war for Arab ears has already begun. Mass pro-government demonstrations in Damascus and Aleppo yesterday illustrated the leadership's determination to mobilise regional opinion in support of what is being portrayed as a confrontation with the US as much as the UN. "Wake up Arabs, your turn will come soon!" said one banner. The officially organised protests were a reminder that despite public dissatisfaction over living standards, 20% unemployment, and falling oil income, the regime still knows how to exploit nationalist sentiment - and faces little conventional political opposition.

Mr Assad's second line of defence follows the Gaullist model: "Après moi, le deluge." This posits that there is no obvious or acceptable successor to the ruling Ba'athists, that he and his late father, Hafez Assad, have succeeded in holding together an ethnically and confessionally disparate country, and that civil war merging with Iraq's could ensue if the regime fell.

Malik al-Abdeh, spokesman for the exiled Movement for Justice and Development opposition party, said such dire eventualities could not be ignored. "The Sunni Salafist movement with its jihadist offshoots is a growing force within Syria, especially among the rural young," he said. "This movement is not under the influence of traditional Islamist parties like the Muslim Brotherhood. It is a relatively new phenomenon, greatly boosted by the Iraq insurgency... it represents the strongest challenge to the regime on the ground."

But Mr Abdeh argued that was a reason to replace Mr Assad, not tolerate him. The US wanted "a more seasoned and pragmatic politician than Bashar" to confront the Islamists, he claimed.

Ms Allaf disagreed. "The Americans are buying into the deluge argument," she said. "They have stopped hinting at regime change. I think a number of countries are telling them this is not the time - even the Israelis. It's in their interest to have a weakened Syria, a Syria on its knees, but not a Syria in chaos."

If all else fails, Mr Assad'could offer a deal involving concessions on Iraq, Lebanon and support for Palestinian militants. But while that might satisfy the US, it could be too much for his Alawite godfathers. In that case, regime change may come not from without but from within.