KILIS, Turkey – Standing just a few strides from the Syrian border, an Iraqi was mingling with Syrian rebel units outside their camp here, trying to find one that would take him in and let him fight in the uprising.

"It's an honor for me," said Sheik Abu Abdullah, wearing the white robe, Islamic skullcap and beard common among Islamic hardliners.

The battle-hungry Iraqi is part of a stream of Arab fighters who have been drawn to the rebel cause, adding not only to the growing complexities of Syria's civil war but also deepening the uncertainties of what could follow Bashar Assad's regime.