There were also reports that the tiny Persian Gulf state of Qatar, carving a reputation as a high-stakes player in Middle Eastern diplomacy and hostile to the Damascus regime, has set up a 2,500-person Arab "intervention force" to bolster the Syrian rebels.
The force, mainly Libyan and Iraqi Islamist fighters, has been airlifted by Qatar to Antioch in southern Turkey near the Syrian border, reported Israel's Debkafile Web site, which has been linked to Israeli intelligence.
Foreign Policy reported that contingencies being considered by U.S. President Barack Obama's administration include the "unlikely option of setting up a no-fly zone in Syria and preparing for another major diplomatic initiative …
"U.S. officials said they are moving cautiously in order to avoid destabilizing Syria further, and to make sure they know as much as possible about the country's complex dynamics before getting more involved."
The Obama administration has been accused of dragging its feet on finding ways to halt the 9-month-old bloodletting inside Syria, where Assad's military and security services have killed more than 5,000 people, mainly civilians shot during anti-regime street protests.
The new initiative is reportedly led by Steve Simon, senior director of the U.S. National Security Council.
Foreign Policy said other options include creating a humanitarian corridor, or safe zone, for fleeing Syrian civilians on the Turkish border, extending humanitarian aid to the rebels, engaging more with the opposition forces and appointing a special coordinator to work with them, as was done in Libya.
"There are many people in the administration that realize the status quo is unsustainable and there is an internal recognition that existing financial sanctions are not going to bring down the Syrian regime in the near future," one official familiar with the initiative told Foreign Policy.
Some Syrian factions are calling for armed intervention, as happened in Libya, a prospect brought closer if the report of the Qatari-backed force is true.
A recent policy paper by the Syrian National Council, the main opposition group, warned that the struggle in Syria "is entering a critical phase … whereby the hope of a continued campaign of passive resistance to an exceptionally brutal and unrestrained regime is becoming more and more akin to a suicide pact."
Defecting Syrian soldiers have established the Free Syrian Army, based in neighboring Turkey, and have reportedly carried out several bombings of state security installations.
But the regime's key military units, such as the Presidential Guard commanded by the president's younger brother Maher Assad, and the vast security apparatus remain loyal to the regime.
There has been no clear sign of any splits within the regime, which is dominated by the minority Alawite sect and established in a 1970 coup by Assad's late father, Hafez Assad, who he succeeded in June 2000.
Few observers in the Middle East give the recent initiative by the 22-member Arab League, long dismissed as a talking shop for dictatorial Arab leaders like Assad, any prospect of negotiating a diplomatic settlement in Syria.
The regime's decision to allow in a 150-strong Arab League observer team is viewed as little more than a delaying tactic by Assad and his henchmen.
The fact that the mission is led by a Sudanese, Lt. Gen. Mohamed Ahmed Mustafa al-Dabi, who has been accused of creating murderous militias that wreaked havoc in the rebellious Darfur region of Sudan, has caused dismay in the Arab world.
Dabi is a former intelligence chief and close associate of President Omar al-Bashir, who is wanted by the International Criminal Court on war crimes charges stemming from Sudan's 1955-2006 civil war. Bashir was named in an ICC arrest warrant issued March 4, 2009.
Few expect Assad and his inner circle to implement the Arab peace plan, since ending the brutal repression carried out in the streets of Syria's cities every day since March 15 would likely spell the end of the regime.
This bolsters moves by militant elements in the opposition for an armed campaign against the regime. That, however, could trigger a civil war between the majority Sunnis and the heavily armed Alawites that could destabilize the entire region.