As the US prepares to withdraw its troops from Iraq by year's end, senior American and Iraqi officials are expressing growing concern that al Qaeda's offshoot here, which just a few years ago waged a debilitating insurgency that plunged the country into a civil war, is poised for a deadly resurgence.
Qaeda allies in North Africa, Somalia and Yemen are seeking to assert more influence after the death of Osama bin Laden and the diminished role of al Qaeda's remaining top leadership in Pakistan.
For its part, al Qaeda in Iraq is striving to rebound from major defeats inflicted by Iraqi tribal groups and American troops in 2007, as well as the deaths of its two leaders in 2010.
Although the organization is certainly weaker than it was at its peak five years ago and is unlikely to regain its prior strength, American and Iraqi analysts said the Qaeda franchise is shifting its tactics and strategies - like attacking Iraqi security forces in small squads - to exploit gaps left by the departing American troops and to try to reignite sectarian violence in the country.
The group, which is also known as al Qaeda in Mesopotamia, has shown surprising resilience even as its traditional supply lines of foreign fighters through Syria have been disrupted by the turmoil in that country, American intelligence officials say.
It conducts a little more than 30 attacks a week, carries out a large-scale strike every four to six weeks, and has expanded its efforts to recruit Iraqis, leading to a significant increase in the number of Iraqi-born suicide bombers.
"I cringe whenever anybody makes a pronouncement that al Qaeda is on its last legs," said Maj. Gen. Jeffrey Buchanan, the American military's top spokesman in Iraq.
"I think one day we are going to look around and say it's been a long time since we have heard from al Qaeda, and maybe then we can say it is on its last legs."
The Qaeda affiliate's nascent resurgence has helped fuel a debate between Pentagon and White House officials, who are eager to close the final chapter on a divisive eight-year war that cost the lives of more than 4,400 troops.