American demands for Assad to step aside have become muted as the war has transformed into a regional free-for-all, with al-Qaida-linked militants dominating the rebel movement and Assad getting backup from Iran and the Lebanese guerrillas of Hezbollah.
The Turkey-based political opposition, crippled by infighting, is in no shape to govern a landscape marked by gun-toting extremists, war-ravaged infrastructure and millions of displaced civilians.
Some analysts contend that the United States could have avoided this scenario by taking more forceful action earlier and building a moderate, Western-friendly force to fight Assad; others praise Obama's reluctance to get entangled in another long-term sectarian conflict so soon after the Iraq War.
Rami Khouri, the director of the Issam Fares Institute for Public Policy and International Affairs at the American University of Beirut, said it was "pretty amateurish policy" to believe that Assad could be dissuaded from resorting to future mass-casualty attacks by limited, carefully calibrated U.S.-led strikes. He said that the United States and its allies are misreading the nature of a regime that is fighting for survival.
"These people don't respond to pinprick, laserlike, finely targeted attacks. It brings about the opposite reaction. I think it would just escalate the situation," Khouri said.
Even as momentum for a military response appears to build at the White House and the State Department, the Pentagon continues to sound a more cautious note.
Speaking in Indonesia, Defense Secretary Chuck Hagel indicated Monday that the United States would be unlikely to take unilateral military action in Syria and said he didn't want to discuss specific responses "until we get all the facts and we are absolutely confident of what happened in Syria." That sounds at odds with Kerry saying the same day that chemical weapons use in Syria was "undeniable."
Gen. Martin Dempsey, chairman of the Joint Chief of Staffs, also has cautioned against a hasty response in letters to Congress. He's stressed that the rebels were not prepared to take charge should Assad's regime collapse.
Richard Haass, a former senior State Department official who now heads the Council on Foreign Relations in New York, said the Obama administration was searching for "a halfway house" a big enough response to deter the regime from further use of chemical weapons, but not so big that "it makes the United States a protagonist in a civil war."
Haass, who was a senior adviser to former Secretary of State Colin Powell from 2001 to 2003 under President George W. Bush, said the most likely response is cruise missiles delivered from sea or by air from U.S. bombers flying beyond the range of Syrian anti-aircraft artillery.
"The use of chemical weapons is a violation of international law, consistent with the Chemical Weapons Convention, which Syria is not even a party to," Haass said, adding that the U.S. could rally its own "coalition of the willing" to sanction a retaliatory response without having to deal with Russia and China's inevitable resistance at the United Nations.
Such a scenario assembling a "coalition of the willing" to punish an Arab dictator for the as-yet unproven use of chemical weapons gives pause to some Middle Eastern states so soon after the war in Iraq.