As top Obama administration officials huddle this week to possibly decide whether to lethally arm Syrian rebels trying to overthrow that country's government, they also must deal with the issue of whether any of the opposition forces can be trusted.
“That’s the $64,000 question,” says Michael Rubin, a former Pentagon official and Middle East expert with the American Enterprise Institute.
The United States has talked for months about the possibility of arming the opposition in Syria’s two-year-old civil war.
However, officials have been reluctant to do so because they don’t want the weapons to get into the hands of Al Qaeda linked fighters or other extremists battling President Bashar Assad’s forces, who now appear to be winning.
Rubin points out the perils the CIA and other U.S. intelligence agencies face when trying to get information about the players in a multi-front, Middle East war, which occasionally means paying the “bad guys” to vet the good guys.
“They’ll say one thing to your face and do another,” he said.
The Free Syrian Army has emerged as the group most likely to receive lethal aid. The group, which consists largely of volunteers and defectors from Assad’s military forces, says its only goal is to topple the regime, with no political or religious agenda.
Arizona Republican Sen. John McCain visited Syria a few weeks ago and talked with Free Syrian leaders. But even that effort underscored the challenges faced in arming rebels, as allegations surfaced that a militant had infiltrated the visit.
“It’s a mosaic of religious and ethnic sects,” Jim Phillips, a Middle Eastern affairs expert with the Heritage Foundation, said recently. “As the so-called Arab Spring continues, the groups that rise up and try to overthrow governments in the region are also divided by ideological differences.”
Secretary of State John Kerry postponed a planned trip Monday to Israel and three other Mideast countries to participate in the White House discussions, said officials who demanded anonymity because they were not authorized to speak publicly on the matter.
The meetings now take on a heightened sense of urgency as Assad's forces are apparently poised for an attack on the key city of Homs, which could cut off Syria's armed opposition from the south of the country.
As many as 5,000 Hezbollah fighters are now in Syria, officials believe, helping the regime press on with its campaign after capturing the town of Qusair near the Lebanese border last week.
While nothing has been concretely decided, U.S. officials said President Obama is leaning closer to signing off on sending weapons to vetted, moderate rebel units, if possible.
Obama already has ruled out any intervention that would require U.S. forces on the ground. Other options such as deploying American air power to ground the regime's jets, gunships and other aerial assets are now being more seriously debated, the officials said, while cautioning that a no-fly zone or any other action involving U.S. military deployments in Syria were far less likely right now.
Such U.S. allies as Britain, France and Israel show no immediate desire to provide lethal aid. But if there is a consensus about who not to arm, it would be the Al-Nusra Front.
Though experienced in guerilla warfare and effective against Assad forces, Al-Nusra is a known terrorist group that the United Nations Security Council recently declared a front for Al Qaeda in Iraq.
Obama also has declared chemical weapons use by the Assad regime a "red line" for more forceful U.S. action. American allies including France and Britain have said they've determined with near certainty that Syrian forces have used low levels of sarin in several attacks, but the administration is still studying the evidence. The U.S. officials said responses that will be mulled over in this week's meetings concern the deteriorating situation on the ground in Syria, independent of final confirmation of possible chemical weapons use.
White House spokeswoman Bernadette Meehan said Obama's advisers were considering all options to hasten a transition in Syria.
Any intervention could have wide-reaching ramifications for the United States and the region. It would bring the U.S. closer to a conflict that has killed almost 80,000 people since Assad cracked down on protesters inspired by the Arab Spring in March 2011 and sparked a war that has since been increasingly defined by sectarian clashes between the Sunni-led rebellion and Assad's Alawite-dominated regime.
It also would essentially pit the United States alongside regional allies Saudi Arabia, Turkey and Qatar in a proxy war against Iran, which is providing much of the materiel to the Syrian government's counterinsurgency and, through Hezbollah, more and more of the manpower.
Syria's precarious position in the heart of the Middle East makes the conflict extremely unpredictable. Lebanon, across the western border, suffered its own brutal civil war in the 1970s and the 1980s and is already experiencing increased interethnic tensions. Iraq, to Syria's east, is mired in worsening violence. And Israel to the southwest has seen shots fired across the contested Golan Heights and has been forced to strike what it claimed were advanced weapons convoys heading to Hezbollah, with whom it went to war with in 2006.
Iran could wreak havoc in the region through its support of Shiite militant groups, and U.S. officials fear Iran may seek to retaliate for any stepped-up American involvement by targeting Israel or U.S. interests in the region.
It's also unclear what American action would mean for relations with Russia, which has provided Assad with military and diplomatic support even as it claims that it was working with the United States to try to organize a Syrian peace conference.
The administration has been studying for months how to rebalance Syria's war so that moderate, pro-democracy rebels defeat the regime or make life so difficult for Assad and his supporters that the government decides it must join a peace process that entails a transition away from the Assad family's four-decade dictatorship.
But Assad's military successes appear to have rendered peace efforts largely meaningless in the short term. While Kerry and his Russian counterpart Sergey Lavrov have been trying to rally support for the planned conference in Geneva -- first envisioned for May and since postponed until July at the earliest -- even America's allies in the Syrian opposition leadership have questioned the wisdom of sitting down for talks while they are ceding territory all over the country to Assad's forces.
Beyond weapons support for the rebels, administration officials harbor deep reservations about other options.
They note that a no-fly zone, championed by hawks in Congress such as McCain, would require the U.S. to first neutralize Syrian air defense systems that have been reinforced with Russian technology and are far stronger than those that Libyan dictator Muammar al-Qaddafi had before he was overthrown in 2011.
And Washington has no clear international mandate for authorizing any strikes inside Syria, a point Obama administration officials have cited since late 2011 to explain U.S. reticence about more forceful action.
The Associated Press contributed to this report.