WASHINGTON Foreign Islamist extremists are streaming into Syria, apparently in response to the Shiite militant group Hezbollah's more visible backing of Syrian President Bashar Assad, a development that analysts say is likely to lead to a major power struggle between foreign jihadists and Syrian rebels should the Assad regime collapse.
Researchers who monitor the conflict said last week that they have detected the influx of foreigners in firsthand observations on the battlefield, spotting them in rebel videos posted on the Internet, observing a recent spike in reported deaths of foreign fighters and studying their postings on social media sites.
And while many foreign fighters have been absorbed into established Syrian rebel groups, there are signs now that an increasing number are remaining in free-standing units that operate independently and are willing to clash with other rebels and Syrian communities to implement their own rigid vision of Islamist governance.
"The numbers are increasing, with more radical groups inside now," said Salman Shaikh, director of the Brookings Institution's Doha Center in Qatar.
Elizabeth O'Bagy, an analyst at the Institute for the Study of War who just returned from a two-week research trip to study rebels inside Syria, said that "without a doubt" she saw far more foreign fighters than on her previous trip two months ago, including foreigner-only fighting groups in northern Idlib province, near the border with Turkey.
"There were substantial groups of foreign fighters that we came across, way more than I remembered," O'Bagy said. "And we heard a lot of commanders complaining about foreign fighters coming in and not working with other opposition groups." Examples of those conflicts appear to be more frequent.
On Friday, the Syrian Observatory for Human Rights, a pro-opposition research center in London, posted a video from Aleppo on Facebook that purportedly shows members of the Nusra Front, a fighting group manned in large part by non-Syrians, replacing a Syrian revolutionary flag with the black flag associated with their al-Qaida-aligned movement. The Observatory noted that "local civil activists have voiced much anger as a result."
Another illustration of jihadists pushing boundaries, O'Bagy said, was the attempt to rebuild a working courts system in a town in northern Idlib. After negotiations, she said, local administrators and Syrian rebels had agreed that ordinary criminal matters would pass through the civilian court system, while the rebel brigades would deal with regime defectors and other war-related cases.
The project exactly the kind of nascent governance the U.S. and other powers want to see in opposition-run territories was undermined when a group of foreign jihadists came to town and took over justice matters, trying suspects based on their own strict interpretation of Islamic law, or Shariah.
"They'd spent quite some time writing up agreements and then these foreign fighters came and disrupted it. They were going with Shariah and undermining the division of labor," O'Bagy said.
Even more ominous was how O'Bagy said the villagers wanted to resolve the problem: "Give us weapons."
While foreign combatants have long been a fixture of the Syrian conflict, analysts said they expected the Sunni Muslim influx to grow in reaction to the Shiite Muslim group Hezbollah's bigger role in shoring up Assad's forces.
In May, Hezbollah leader Hassan Nasrallah pledged "tens of thousands of fighters" to defend Assad's regime. Those fighters were considered crucial in the two-week-long battle over the strategic town of Qusair, which fell to Hezbollah and Syrian government forces last week after more than a year in rebel hands.
Nasrallah's justification for joining the war made mention of all the foreign jihadists who have poured into Syria to fight for the rebels an uncomfortable truth for the Obama administration as it struggles to come up with a Syria policy that bolsters moderates while isolating extremists.
Latest figures from the Syrian Observatory for Human Rights, which is generally regarded as the most authoritative recorder of Syrian casualty figures, showed that 2,219 foreigners have been killed fighting on the rebels' behalf since the conflict began. That's more than the 1,965 dead who were identified as defectors from the Syrian army.
"Meanwhile, Hezbollah's involvement was considered a foreign interference," Nasrallah scoffed in his speech last month.
After Nasrallah's speech, Sunni clerics across the region called for men to head to Syria to help their Sunni brethren against the Shiite "Party of Satan" a play on Hezbollah's name, which means "Party of God" and Assad's minority Alawite sect.
The most prominent was Sheikh Youssef al-Qaradawi, a Qatar-based cleric with a millions-strong following and close ties to the Muslim Brotherhood. News reports quoted him as telling a rally in Doha that "every Muslim trained to fight and capable of doing that" should make himself available for jihad against Assad and Hezbollah.
"I wouldn't be surprised if we'll see higher flows, especially after the statement of Qaradawi," said Aaron Zelin, who researches militants for the Washington Institute for Near East Policy and blogs about them at Jihadology.net. "He's a pretty popular mainstream cleric in the region. He's not fringe, he's got weight behind him."