Debate is intensifying in Washington over the group that stands to reap the most immediate benefits from a U.S. military intervention in Syria -- the Free Syrian Army, the leading alliance of rebel factions fighting to topple Bashar Assad.
While the U.S. already is providing money, equipment, training and limited weaponry to the Free Syrian Army (FSA), some U.S. military officials are growing increasingly concerned about the presence of extremist Islamic groups within the overall force. A U.S. military strike, even a limited one, could tip the balance in the civil war in favor of the rebels, they argue, potentially propelling these or other radical Islamic groups into a position of power in a post-Assad Syria.
The difficulty determining where the FSA’s sympathies lie resides in the fact that it is an army in name only. It is made up of hundreds of small units, some secular, some religious – whether mainstream or radical. Others are family gangs, or simply criminals.
The FSA is by far the largest Syrian rebel force. U.S. Secretary of State John Kerry and Sen. John McCain have both estimated the total rebel force in Syria at around 100,000. They claim the hardcore Islamists -- defined as members of two al Qaeda-affiliated groups waging war against Assad -- account for only 10 to 15 percent of that total.
“Most of the groups battling against Assad are composed of Islamist fighters, but only a small minority could accurately be characterized as extremist,” a U.S. official told NBC News, speaking on background.
But a senior military official, also speaking on condition of anonymity, disagreed, claiming the percentage of radical Islamic fighters is “way higher than that,” when the definition is expanded beyond the membership of the al Qaeda affiliates. He said Pentagon officials estimate that extreme Islamist groups now constitute “more than 50 percent” of the rebel force, “and it’s growing by the day.”
Such debate misses the point, said Roger Cressey, a former National Security Council staff member and an NBC News counterterrorism consultant.
"It's jihadi voodoo math," he said. "… The real issue is what influence do they really have? Are they just street fighters or do they have influential positions? What are their ties to outside entities? Do we know?"
The “commander” of the FSA, Brig. Gen. Salim Idris, is a former Syrian Army general who defected in July 2012. He is seen as the leader of the most moderate segment of the FSA and under his leadership the group has been receiving limited assistance from the U.S. -- small arms like AK-47s, ammunition, military rations, medical kits and cash, but not much more.
Idris acts more as a chairman of the board than a battlefield commander, offering advice and money to other groups that he feels are benefiting the cause. But he and his senior aides don’t do much vetting of groups or individuals wanting to join the fight, being focused more on winning than on developing a litmus test for membership. Those decisions are typically made by local commanders, say numerous rebel fighters interviewed by NBC News.
Publicly, the FSA says it wants to oust Assad so that it can create a state that is prosperous and tolerant of its religious minorities, including the Alawites, who have ruled Syria for decades even though they make up less than 15 percent of the population. It also rejects, leaders say, the radical philosophy of al Qaeda-linked groups like the al-Nusra Front and the Islamic State of Iraq and the Levant, both of which are listed by the U.S. as terrorist groups.
But Idris told NBC News recently that such proclamations don’t mean all FSA factions consider the Western powers to be friends. “There are some groups, jihadi groups, who are now making statements and propaganda that they are fighting the regime,” he said. “They are fighting for their own interests.”
Some FSA factions aren’t shy about advertising their radicalism, at least on some venues. An example is the al-Aqsa Islamic Brigades, a unit of the FSA, which posted an illustration of masked jihadis marching away from a burning U.S. Capitol on its Facebook page.
President Barack Obama and other U.S. officials have said that any U.S. reprisal for Assad’s alleged use of chemical weapons against his people would be limited and not aimed at regime change.
But Cressey, the NBC News consultant, and other experts say that attacks – likely to be in the form of cruise-missile strikes on Syrian command-and-control facilities -- could have that effect, coming at a time when the rebels have been gaining ground, even making headway in Alawite strongholds like Latakia.
"You don’t have to advertise regime change," said Cressey, "but you can strike a series of targets that are critical to the regime's survival, that ultimately will help the rebels.
Adding to U.S. concerns about the stability of the FSA are recent reports of internecine warfare between the FSA and rival hard-core Islamic rebel groups.
In one incident about a month ago, a witness in the town of Raqqa told NBC News that fighting broke out between fighters from one of the al Qaeda-linked groups and FSA units, causing casualties on both sides.
“These were not skirmishes, I cannot call it anything other than actual fighting," said the witness, who asked to remain anonymous. The fighting only subsided after tribal elders and other rebels groups in the city brokered a truce between the groups to “prevent the blood of the civilians’ being spilt,” said the witness.
Reservations over the FSA’s makeup, which may account for the United States’ half-hearted embrace of the group, have undercut the ability of Idris’ faction to set the agenda for the organization, his aides tell NBC News.
They cite the U.S. restrictions on weaponry as an example. Many Syrians say if Idris had more guns, more money and bigger weapons, fighters would happily join him. But since he doesn’t, they argue, he is just one player among many, and therefore is unable to unify command of the rebel forces.
But privately, even some members of moderate factions within the FSA, who distance themselves from the radicals in public, say they are critical to the uprising.
“There is a dire need for them because they follow the martyr jihadi approach," one activist who goes by the name Ahmad told NBC News. "They have no problem if three or four of them get martyred for the cause, even if the operation was against a small military post. They are always in the front lines, they are well equipped and well trained and they help the FSA a lot. … They are like a man who does not tire.”