At the United Nations, Russian Ambassador Vitaly Churkin speaks to U.S.… (Mario Tama / Getty Images )
After pressing for 16 months for a change in government in Syria, the Obama administration is scrambling to prevent growing bloodshed and the apparent unraveling of President Bashar Assad's hold on power from paving the way to regional calamity.
A day after the brazen assassination of three top military aides suggested armed insurgents had begun to gain the upper hand, Assad appeared on state-run TV on Thursday to show he was alive as heavy fighting continued for a fifth consecutive day in parts of the capital, Damascus.
With a diplomatic solution now considered all but impossible, U.S. officials and their allies reached out to opposition leaders to seek a peaceful transition to a new government in the event Assad is toppled.
U.S. officials also conferred with Israeli leaders and urged them not to use military force to try to secure Syria's stockpiles of chemical weaponry, arguing that such an intervention would probably rally support for Assad at home and in the Arab world.
Some U.S. officials fear that Assad's security forces, which have repeatedly fired heavy weapons in civilian areas, could further up the ante by using blister agents and poison gas against opposition forces if they believe the government is about to collapse.
Divisions among world powers were painfully evident as Russia and China again vetoed a Western-supported United Nations Security Council resolution on Thursday that would have imposed economic sanctions if Assad's military refused to observe a cease-fire and remove heavy weapons from populated areas.
Jay Carney, the White House press secretary, said Russia and China were "on the wrong side of history.... It is a mistake to prop up that regime as it comes to an end."
Analysts said the 11-2 vote, with two abstentions, made it clear that Moscow won't abandon its longtime ally in Syria, home to Russia's only overseas navy base. As a result, the months-long effort by Washington and its allies to forge a diplomatic solution to the crisis apparently has reached a dead end.
It may also spell an end to diplomatic efforts led by envoy Kofi Annan, and the 300 unarmed monitors that the U.N. sent to Syria during the spring in an unsuccessful attempt to protect civilians and quell the mounting violence in the rebellion.
U.S. officials worry now that a victory over Assad, a member of the minority Alawite sect, by Sunni Muslim insurgents could spark a sectarian bloodbath. Another risk comes from Islamist militants, including some from Al Qaeda, who have begun to assert themselves amid the country's chaos.
Some U.S. officials and diplomats said Assad could still hold on for some time, and that the outcome was far from clear. They said that if insurgents continue to gain ground, Assad and his aides may abandon Damascus for the coastal province of Latakia, a stronghold for Alawites, whose sect is an offshoot of Shiite Islam. On Thursday, some media and opposition reports placed Assad in Latakia.
Andrew Tabler, a Syria expert at the Washington Institute for Near East Policy, predicted the government would make a "strategic retreat" to the coast. "I'm a little skeptical about things collapsing quickly," he said.
Analysts say the course of the fighting is likely to be the most decisive factor in determining the fate of Syria. Many observers see the momentum now favoring the rebels, despite the government's advantages in armor and weapons.
While arguing that the ongoing battles in the streets of Damascus will hasten Assad's fall, opposition activists sought to allay concerns that Syria could descend into an Iraq-style abyss of chaos and sectarian killings should rebels capture the capital.
"We've been preparing for the end of the Assad regime for a long time," Abdulbaset Sieda, head of the opposition Syrian National Council, told Reuters news agency. "Our aim is to reach that phase with minimal losses. We have plans on the economic, administrative and social levels, and we are certain we can do it."
The most immediate concern may be the chemical weapons. AU.S. militaryofficial said that Syria has shifted some of its chemical agents from storage bunkers in recent weeks, but he said it's unclear whether they were moved to prevent them from falling to the rebels, in preparation for use or some other reason.
Israeli officials have hinted for months that they would launch airstrikes to destroy the stockpiles, if necessary, to keep them out of the hands of Islamist extremists. But some experts have warned that airstrikes might release the poisons into the atmosphere.
Israeli authorities on Thursday canceled weekend leaves for soldiers. The defense force began shoring up defense and emergency response teams deployed along the Golan Heights border with Syria, officials said.
Defense Minister Ehud Barak said Israel was concerned about the safety and control of Syria's chemical weapons and long-range missiles.