"It's not clear right now the extent to which al-Qaida extremists are working with the Syrian opposition"

The group has longstanding ties to Syria, and its early members weren’t just Iraqis; many of them were Syrians. The former leader of al-Qaida in Iraq, Abu Musab al-Zarqawi, not only established a network of fighters in Syria, but he also folded them into his northern Iraqi faction of al-Qaida.

“Al-Qaida’s arm in Iraq has maintained those relationships,” says Juan Zarate, a former deputy national security adviser for terrorism who is now at the Center for Strategic and International Studies. “This is very much a strategic opportunity for al-Qaida. Al-Qaida is very good, like a parasite, at taking advantage of this kind of conflict.”…

The situation is so murky because during the Iraq War, al-Qaida used a network of Syrian tribesmen and smugglers to get suicide bombers into Iraq to attack U.S. forces. Now that so-called “rat line” has been reversed; al-Qaida is starting to send operatives the other way — back to Syria.

“Assad allowed that rat line to flourish, and he fed the jihadi beast in Iraq,” said Zarate, who was a national security adviser in the Bush administration during the war. “And that beast is now coming back to bite him.”