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.
Indeed, there are signs that the proliferation of radical groups has led the U.S. to consider a future in which Assad stays in power in Syria.
In an op-ed column published last month in The New York Times that was widely criticized by Syrian opposition figures, U.S. career diplomat Ryan Crocker suggested Assad is better than the alternative: a major country at the heart of the Arab world in the hands of al-Qaida.
"We need to come to terms with a future that includes Assad -- and consider that as bad as he is, there is something worse," wrote Crocker, who served as ambassador in Iraq and Syria.
Al-Qaida fighters and other Sunni extremists were largely routed in many parts of Iraq following the start of the U.S. military's surge strategy in 2007 that involved an influx of American troops and support from Iraqi forces, including Sunni militiamen opposed to the group's extremist ideology.
The group has come roaring back since the responsibility of securing the country fell to Iraqi forces once U.S. troops departed.
The Islamic State of Iraq and the Levant and another powerful al-Qaida-linked group in Syria, the Nusra Front, operate as independent groups. Both, however, have pledged allegiance to al-Qaida's leader, Ayman al-Zawahri.
Not much is known about the operational activities of the Islamic State of Iraq and the Levant, but it is believed to get its funding from wealthy Gulf donors and internal sources, including smuggling and extortion, and its recruits are mainly from Iraq's Sunni heartland as well as foreign fighters from al-Qaida's networks in Pakistan and Afghanistan. Its ultimate goal is to establish a Islamist state in the region, regardless of current borders.
Sunnis across Iraq, Syria and Lebanon, many of whom have centuries-old tribal affiliations spanning the long and porous border, feel they have been marginalized by their respective governments, which they see as too closely allied to Shiite powerhouse Iran.
"What we're seeing in Iraq is really longstanding sectarian tensions that we all are very familiar with, and they're being exploited, quite frankly, by terrorists operating in Syria. These are the same groups," U.S. State Department deputy spokeswoman Marie Harf told reporters Monday.
In an audio recording released on the Internet Wednesday, a spokesman for the Islamic State of Iraq and the Levant vowed to crush the rebel factions fighting in Syria and declared war on Shiites in Iraq, Syria, Lebanon and Yemen.
Despite the burst of strength across the region, global intelligence company Stratfor predicted a bleak future for the group.
"For all the dedication and motivation of its fighters, ISIL simply does not have the manpower or the force to overcome its innumerable enemies and achieve its end goals of establishing its version of an Islamic caliphate in Syria and Iraq," it said in an analysis.
The infighting in Syria, although brewing for a long time, has been linked to the upcoming peace conference in Geneva.
Imad Salamey, a professor in international relations at the Lebanese American University, said the Syrian opposition has realized that the Islamic State of Iraq and the Levant is a major liability -- not just for the image of the opposition but also for turning Syrians against the opposition.
He said the Syria war is forcing changes and power struggles that will have a major and lasting regional effect.
"The entire political order of the Middle East is being renegotiated," he said.
Associated Press writer Adam Schreck contributed to this report.