BEIRUT (AP) -- Al-Qaida is positioning itself as a vanguard defending the Sunni community against what it sees as persecution by Shiite-dominated governments across Syria, Lebanon and Iraq.
As a result, a Syrian rebellion whose aim was the removal of President Bashar Assad is evolving into something both bigger and more ambiguous: a fight increasingly led by Sunni jihadis -- often foreign and animated mainly by hatred of Shiites -- who are determined to create an Islamic state.
Battling these extremists is a coalition that includes moderates who are horrified that their rebellion in Syria has been discredited, with parts of the country falling under strict religious law.
For moderates in the Middle East, the renewed assertiveness of the extremists is increasingly taking on the aspect of a regional calamity.
"The war in Syria has poured gasoline on a raging fire in Iraq, and conflicts in both countries are feeding upon one another and complicating an already complex struggle," said Fawaz A. Gergez, director of the Middle East Center at the London School of Economics. "Now the reverberations of the Syria war are being felt on Arab streets, particularly Iraq and Lebanon, and are aggravating Sunni-Shiite tensions across the Arab Middle East."
Why now? Experts see a fundamental al-Qaida characteristic of feeding on social, religious and ideological cleavages -- of the kind that have been exposed in spectacular fashion in the Sunni-Shiite divide in Syria. It is fed by a vicious circle hugely frustrating to the moderate mainstream rebels: the more the West shows reluctance to intervene -- fearful that helping them means also aiding global jihad even indirectly -- the more there is a void for the jihadis to step into, capitalizing on the widening sectarian schism to recruit new fighters.
The al-Qaida-linked group that calls itself the Islamic State of Iraq and the Levant has made no secret of its desire to turn Syria's civil war into a regional conflagration that would allow it to take firmer root. Its very name, rebranded last year from the more-local Islamic State of Iraq, spells out its cross-border ambitions.
Even as its fighters were busy seizing territory in Syria, it has been dramatically escalating its operations inside Iraq, carrying out mass-casualty attacks and staging a series of audacious prison breaks that freed more than 500 inmates. Many of those were jihadists who are believed to have flowed back into the group's ranks.
This week, fighters of Islamic State of Iraq and the Levant overran the city of Fallujah and parts of Ramadi in Iraq's Sunni-dominated Anbar province, which stretches west to the border with Syria. This triggered fierce clashes with Iraqi special forces and government-allied Sunni tribes trying to recapture the strategic territory.
The al-Qaida gains pose the most serious challenge to Prime Minister Nouri al-Maliki's Shiite-led government since the departure of U.S. forces in late 2011.
In Lebanon, where Iranian-backed Shiite Hezbollah guerrillas have helped shore up Assad's forces in Syria, the Islamic State of Iraq and the Levant claimed responsibility last week for a suicide car bombing that killed five people in a Hezbollah bastion of Beirut.
Ahmad Moussali, a professor of political studies at the American University of Beirut, said the vacuum left by the U.S. in 2011 in Iraq and the beginning of the uprising in Syria has led al-Qaida to see in Syria and Iraq an arena for war, as well as the possibility of establishing an Islamic state.
"This is why we are seeing today the congregation of all sorts of al-Qaida-type groups as well as other radical groups coming to Syria and Iraq as well as Lebanon today, and the danger is that these groups have been getting a lot of success," he said.
The rapid rise inside Syria of the Islamic State of Iraq and the Levant over the past year has dampened Western support for the rebels. Its brutal tactics have alienated other factions fighting to topple Assad, enough to ignite this week some of the most serious rebel infighting since the start of the uprising in March 2011.
The clashes have pitted a consortium of rebel groups in Syria, including Islamic factions, against the group, spreading to most parts of northern Syria and leaving hundreds of people dead in five days.
The fighting has shaken the group, which lost two of its headquarters in the northern cities of Aleppo and Raqqa this week. Many now openly accuse the group of hijacking their revolution and indirectly serving Assad's interests. Some go as far as saying it's an Assad invention.