WASHINGTON - With the US election over and Syria's civil war growing bloodier and spreading, the Obama administration is quietly re-examining its options for involvement in the conflict.

Whether that will lead to a change in strategy remains unclear. President Barack Obama and his advisers are extremely cautious, current and former officials involved in discussions say.

But those who favor greater US involvement - not least Syrian opposition leaders - clearly believe their time has come. What Washington must consider, they say, is more support for the rebels and perhaps limited military action.

Even with electoral pressures gone, a major deployment of US troops remains unthinkable. The kind of more limited but sustained air campaign that helped oust Libya's Muammar Gaddafi is also off the table, at least for now.

Arming the rebels, the Obama administration says, might simply make matters worse - particularly given the mounting evidence of a growing Islamist presence, increasing sectarian bloodshed and accusations of rebel war crimes.

But simply standing on the sidelines may also no longer be viable. As the body count has mounted in Syria, there have been growing signs the war is also destabilizing neighboring states, particularly Lebanon but also Iraq, Turkey and Jordan.

This weekend Syrian and Israeli forces traded fire across their border in the Golan Heights.

"I'm amazed by how quickly people have started talking about Syria" after the election, said Joseph Holliday, a former US Army intelligence officer and expert on the Syrian opposition at the Institute for the Study of War who frequently briefs American officials.

"I think there's a feeling that doing nothing is in itself a choice, and that the longer we hold back the worse things are getting."

With Syrian President Bashar al-Assad increasingly using helicopters and jets against civilian targets, there is growing talk of some form of "no-fly zone" - or perhaps a series of targeted strikes to damage his air force.

A likely request by Turkey for US Patriot ground-to-air missiles to defend its airspace could also see US troops deployed in its territory within miles of the Syrian border.

The new united rebel leadership announced this weekend in Doha - the result of months of pressure from western states and Arab allies - is also seen as offering the best hope so far that the opposition can form a united front.

Discussions being held within the State Department, Pentagon and elsewhere are not, insiders say, part of a centrally ordered policy review.

"We constantly review options," one senior administration official told Reuters, although he said there was no change in the White House's opposition to arming the rebels directly.

Another US official knowledgeable about Washington's Syria policy confirmed, however, that a post-election revision was under way.

"The question is: what to do?" he said.

THINKING THE UNTHINKABLE?

A few senior US figures, such as Susan Rice, the UN ambassador touted as a potential new secretary of state to replace Hillary Clinton, are reported to be more supportive of drastic action. The US military and intelligence agencies, insiders say, are much more reluctant.

Even if Assad were to go, they worry the country might tear itself apart in ethnic bloodletting that could go on for years.

Obama himself has shown little appetite for new foreign interventions, and approaches his second term with no shortage of domestic challenges.

But the shifting reality on the ground in Syria, some argue, may be opening up new options.

One of the greatest barriers to greater involvement in the conflict, Western officials have long complained, has been the chaotic and disunited nature of the rebels - as well as their persistent failure to perform on the battlefield.

But that may now be changing. Disparate elements of the Free Syrian Army are increasingly seizing ground and holding it against Assad's forces. The newly created Syrian National Coalition for Opposition and Revolutionary Forces, under reformist Damascus cleric Mouaz Alkhatib, must build on those victories.

Long-term Assad supporter Russia, some experts say, may be tiring of the Syrian leader. Moscow might have little appetite for Western-backed overthrow of Assad, but it also wants to make sure it retains influence with any government that replaces him.

'WAITING FOR THE WEST'

Some key allies remain reluctant. British officials have also been re-examining their Syria options, British sources say, but this week they rolled back from suggestions they might arm the rebels or ease a European arms embargo. France has yet to make good on statements it might provide anti-aircraft weaponry.

But Saudi Arabia, Qatar and Turkey - all arming the rebels - may be betting on a US policy shift that would bring European powers along and help them not just in Syria but in their region-wide rivalry with Assad's ally Iran.

Up to now, their support for the rebels has largely been limited to intelligence agents and rich Arab individuals cutting deals to arm and supply whichever groups they fancy. That, many experts say, has strengthened the hand of the Islamists.

The opportunity now, rebel supporters say, is for a much more coordinated strategy perhaps led by Washington.

They "are waiting for the West," Salman Shaikh, a former adviser to the Qatari royal family and now director of the Brookings Doha Center, said via video link. "They don't want to be in this alone. Only the US can bring this about." ? ?

The fact that Turkey held back from talking about a Patriot missiles request until the day after the US election may be no coincidence. While theoretically defensive, the range of the missiles would reach well inside Syrian airspace.

The option of using Turkish-based Patriot batteries to enforce a limited "no-fly zone" over nearby rebel territory is, insiders say, already circulating within the US government.

Deploying the missiles, however, would require stationing dozens if not hundreds of US troops in volatile border regions already swarming with refugees and weapons.

"There is undoubtedly going to be more attention placed on Syria by the administration in the aftermath of the election," says Ari Ratner, a former Obama administration State Department appointee and now a fellow at the Truman National Security Foundation. "Not least because the situation on the ground and the needs of our allies will only escalate."