WASHINGTON -- Despite Americans' exhaustion with 11 years of foreign conflict, the victor in Tuesday's presidential race may find it all but impossible to keep the United States from becoming more deeply entangled in the unfolding calamity of Syria's sectarian civil war.
Pressure for Washington to play a greater role comes from a variety of factors: soaring casualty tolls, hundreds of thousands of refugees flooding into neighboring countries, wholesale destruction of Syria's infrastructure, the growing presence of al-Qaida-linked fighters, fears that violence will spill over into adjacent nations, and the danger that the Assad regime will collapse, leaving Syria's chemical weapons open to theft.
"The longer this continues, the more sectarian violence is going to take place," warned F. Stephen Larrabee, an analyst with the RAND Corp., a policy institute. "Sooner or later, the U.S. will arrive at a tipping point where it will have to decide if it will watch from the sidelines as the situation deteriorates or has to take some sort of action."
Moreover, experts said, having committed themselves to Syrian President Bashar Assad's ouster, President Barack Obama and Republican hopeful Mitt Romney would have to do more to make certain that goal is achieved. Otherwise, they risk appearing weak and feckless, leaving the U.S. little leverage to shape a post-Assad regime and less influence in the oil-rich region. Such an outcome also could embolden al-Qaida and allied groups.
"Our Arab allies have shown some willingness and sensitivity toward the U.S. administration's reluctance to get involved because of the election," said Randa Slim of the Middle East Institute, a Washington-based research center. "But after the election, we will see the Gulf (Arab) allies increase pressure on the U.S. to do more. I think we will see the same from the Turks."
Obama and Romney both have ruled out U.S. military intervention. So the next president will have limited options to contain the mayhem. Those could include more robust efforts to force feuding opposition leaders to agree on the makeup of an alternative government and to identify moderate rebels to whom to channel heavy weapons. The U.S. and Turkey also could deploy anti-aircraft batteries along Turkey's side of the border to protect civilians and rebels across a swath of northern Syria in a "safe zone" that wouldn't require U.N. approval, experts said.
Such a zone "is going to change the balance of power. The only way Assad can project power in northern Syria today is by bombing with airplanes and helicopters," said Joshua Landis, a Syria expert at the University of Oklahoma. "If you take that out ... then you are getting closer to a ... situation where the rebels can set up camp and welcome (Syrian army) defectors in a safe environment. They could train and recruit."
Such options also could end up sucking the U.S. even deeper into the maelstrom pitting rebels mostly from Syria's Sunni Muslim majority - backed by Saudi Arabia, Qatar, Turkey and Islamists from across the region - against regime forces led by Assad's Alawite minority, a Shiite Muslim offshoot, backed by Iran's Shiite rulers and Hezbollah, the Shiite movement that dominates Lebanon's government. The Shiite-led government of Iraq might also side with the Assad allies.
"The danger is that you have a wide chessboard and lots of moving pieces," said a senior Arab diplomat who requested anonymity in order to speak freely. "The situation is very serious and fast-moving."
The crisis could easily reach a point "where the downside risks of doing nothing begin to outweigh the risks of doing something," Larrabee said.
A re-elected President Obama could develop a new strategy faster than a newly elected Romney, who'd need months to seat his full national security team and conduct a policy review, the senior Arab diplomat noted.
Neither Obama nor Romney has spent much time during the campaign discussing the bloodiest of the Arab uprisings that have upended the Middle East. But both largely espouse the same approach: oust Assad and stop Syria from becoming an Islamist haven by using the CIA to steer Saudi- and Qatari-supplied arms to moderate rebels while trying to unify disparate opposition leaders with the credibility to be a government-in-waiting that would participate in a U.N.-led peace effort.
Obama has sent a U.S. military task force to Jordan's border with Syria to help Jordan forge contingency plans in case of a spillover of serious violence, and he has slapped sanctions on the regime to strangle its arms buying. The United States also has provided more than $132 million for assistance to hundreds of thousands of refugees - estimates place the number between 360,000 and perhaps 700,000 - outside Syria and the millions of people - somewhere between 1 million and 10 million - who've been forced from their homes by the fighting and are now scrambling to find food, shelter and medical care.
The U.S., however, has rejected calls to impose a no-fly zone to ground Assad's airpower and refuses to supply heavy weapons, including shoulder-fired anti-aircraft missiles, to the rebels, fearing the weapons would end up in the hands of al Qaida-linked Islamists.
The bloodletting -- estimates of the dead are nearing 40,000 and may be much higher -- also is having a corrosive effect on U.S. relations in the region, experts said. Both Turkey and its Arab allies, frustrated by what they consider a standoffish U.S. role, are outrunning current policy.
"The U.S. has lost a lot of leverage and it's coming into this particular game too late," said Ammar Abdulhamid, a Syrian dissident and fellow at the Foundation for the Defense of Democracies, a center-right policy institute in Washington.
Still, he and other experts said, the U.S. can't stop exploring its options, especially with the war heating up sectarian tensions in Lebanon, where there have been gunfights between Alawites and Sunnis and an Oct. 19 car-bomb assassination in Beirut of a senior Sunni police official that many blamed on Syria and Hezbollah.
The war also is infecting Iraq, threatening to upend the tenuous stability that the U.S. fought for nine years to secure. Iraqi Sunni militants are siding with Syrian rebels, Shiite extremists are fighting for Assad, and the Shiite-run Baghdad government is reportedly allowing Iran to send arms to Damascus across its territory and airspace, stoking frictions with Saudi Arabia and other Sunni Arab regimes.
Turkey, meanwhile, has made clear that it won't tolerate Syria's minority Kurds setting up an independent enclave in northeast Syria that is run by the Syrian wing of Turkey's Kurdish rebels and that could enflame Kurdish separatism in Iraq and Iran. In recent days, Syrian Kurdish militia have clashed openly with anti-Assad rebels near Aleppo.
"There are no good choices in Syria," said Landis of the University of Oklahoma. "It's a minefield. Whoever is president after Nov. 6 is going to have to tiptoe through this minefield. We have to take this one step at a time and figure out who is who on the ground."
The senior Arab diplomat said the most dangerous threat demanding greater U.S. attention is the possibility of a precipitous collapse of Assad's rule that could see his army disintegrate. That would leave the country's stockpiles of sarin, VX and other chemical weapons open to theft by al-Qaida-linked militants, who could use them against the U.S. or its allies, or Iran-backed Hezbollah, which could use them against Israel.
"The chemical weapons threat is much more on your doorstep than anything else," he said. "If Hezbollah gets its hands on these chemical weapons, it will be much more of a threat to Israel than the Iranian nuclear program."
U.S. officials say they are closely monitoring those stockpiles, and Obama has warned Assad that he will face U.S. military intervention if he uses them or moves them. Yet how Washington would prevent the weapons from falling into the wrong hands should the regime implode remains unclear.
The Obama administration is now preparing a post-election effort to build a credible Syrian opposition leadership. Secretary of State Hillary Rodham Clinton on Wednesday made clear that the U.S. no longer considers the Syrian National Council, which is comprised primarily of exiles, as the primary anti-Assad umbrella group and instead is promoting the formation of an interim government that includes "those who are in the frontlines fighting and dying today."
But the initiative has already run into trouble, with Syria National Council members furious at being shunted aside by an administration they think has done too little to help topple Assad. The administration's move is certain to color a Syrian opposition meeting to be held in Qatar next week.
"I believe America does not want to do anything, but to allow Bashar Assad to destroy Syria," said Haythem al-Maleh, a former judge and political activist. "Only in Syria can the army kill people without any limit, with people of the world just looking on."
-- Roy Gutman in Istanbul contributed to this report.