Al-Qaeda has advanced beyond isolated pockets of activity in Syria and now is building a network of well-organized cells, according to US intelligence officials, who fear the terrorists could be on the verge of establishing an Iraq-like foothold that would be hard to defeat if rebels eventually oust President Bashar Assad.
At least a couple of hundred al-Qaeda-linked militants are already operating in Syria, and their ranks are growing as foreign fighters stream into the Arab country daily, current and former US intelligence officials say according to media reports.
The units are spreading from city to city, with veterans of the Iraq insurgency employing their expertise in bomb-building to carry out more than two dozen attacks so far, the reports added.
Others are using their experience in coordinating small units of fighters in Afghanistan to win new followers.
In Syria on Friday, insurgent commanders appealed anew for new and better weapons from abroad, complaining that Assad's forces have them badly outgunned from the air and on the ground.
“In fact, rebel leaders say that with so little aid coming to them from the US and other nations, they are slowly losing the battle for influence against hardline militants. They say their fighters are sometimes siding with extremists who are better funded and armed so they can fight the far stronger Syrian army,” News 24 Website said.
It all could point to a widening danger posed by extremists who have joined rebels fighting the Assad government, it added.
Rand analyst Seth Jones said the presence of extremists was small but growing. He said the US should consider using its forces or getting the rebels or a regional proxy to attack the al-Qaeda units.
"There has been talk that some operatives in Pakistan are saying, 'Why don't we see if we can make it to Syria,'" he said. "That's where the fight is."
If they win local loyalty by fighting alongside Syrian rebels, they will be hard to eliminate no matter how Syria's future pans out, said former CIA analyst Riedel.
"Look at Iraq, where we decimated them time and again," Riedel said. "They're still there."