Al Qaeda in Iraq, the Osama bin Laden-inspired terrorist group that sank the country into sectarian violence five years ago, is trying to make a comeback in post-U.S.-occupied Iraq, analysts and intelligence officials say.

Washington is closely watching whether AQI, as it is called, in the next year can reassemble networks smashed by the U.S. counterterrorism campaign. American commandos and intelligence officers killed AQI leader Abu Musab Zarqawi in 2006 and then scores of other chieftains until, by 2011, the group was decimated.

But right after the last U.S. troops left Iraq in mid-December, the Sunni Muslim AQI claimed responsibility for a string of deadly attacks, primarily against Shiites, whose sect dominates Iraq's government. Last week, an AQI spokesman claimed that it had carried out multiple bombings that killed 55.

A U.S. official told The Washington Times that AQI is carrying out more attacks this year than it did in the second half of 2011, when the U.S. military was pulling out. But the increased violence does not mean AQI is back to its old strength, the official said.

Iraqi Prime Minister Nouri al-Maliki, a Shiite, provided AQI and the minority Sunnis a recruiting mantra when he ordered the arrest of the country’s highest-ranking Sunni leader the day after U.S. troops exited.

“I think AQI, which had been severely battered by the U.S.-led counterinsurgency campaign, has regained strength,” said James Phillips, a Middle East analyst at the Heritage Foundation think tank. “The Iraqi government, dominated by Shia political parties, has greatly contributed to AQI’s revival by undercutting and persecuting Sunni politicians and tribal leaders.

“This has strengthened AQI’s limited appeal inside Iraq and allowed it to position itself more convincingly as the champion of Sunni Arabs against the Maliki regime, which is aligned with Shia Iran.”

Expanding influence

A sign of al Qaeda in Iraq’s resilience is that it has had the manpower to send operatives inside Syria to target President Bashar Assad’s regime. Al Qaeda thrives in power vacuums, something a deposed Mr. Assad might create.

“AQI, which always included many Syrians, Saudis, Jordanians and Yemenis, also is increasingly active inside Syria, where it seeks to pose as the champion of Sunnis against the Alawite-dominated Assad regime,” Mr. Phillips said. “AQI had developed smuggling routes that brought jihadists, money and supplies into Iraq through Syria.

“Now it is moving men, weapons and supplies across the border in the other direction, supported by Sunni tribes that straddle the border.”

The Assad family belongs to Syria’s minority Alawite Muslim sect, while the country is majority Sunni.

CIA Director David H. Petraeus told Congress last month that “al Qaeda in Iraq has been a bit more active than it was for quite some period.”

Army Lt. Gen. Ronald Burgess, who heads the Pentagon’s Defense Intelligence Agency, testified that Iraq’s counterterrorism ability still needs U.S. help because AQI “is a capable and formidable foe.”

“While the Iraqis have some capability, there are certainly some things that we are still looking at doing to help them from an intelligence standpoint,” he said.

Sen. John McCain, Arizona Republican, who criticized President Obama for not negotiating a longer stay for U.S. troops, said AQI is quickly getting stronger.

“Violence is up significantly since the departure of U.S. troops,” said Mr. McCain, the ranking member of the Senate Armed Services Committee. “Al Qaeda in Iraq and violent Shia extremist groups are still very much active and threatening to Iraq’s stability. It is increasingly difficult to argue that Iraq, to use the president’s words, is, quote, ‘stable and self-reliant.’ “

“Just consider the scale and scope of these risks,” the senator said. “Despite the remarkable damage inflicted on al Qaeda’s core leadership by our military and intelligence professionals, al Qaeda officials - affiliates in Iraq, the Horn of Africa and the Maghreb - are growing stronger, more independent, more diffuse and more willing to attack American interests.”

Ramzy Mardini, an analyst at the Institute for the Study of War who tracks Iraq’s post-U.S. crisis, notes that AQI is not bombing just Shiites. It also has stepped up its assassinations of members of the Awakening Movement begun by Sunni local leaders to combat insurgents.

Mr. Mardini said four were killed during one week in January. They included Mullah Nadim al Jubouri, who defected from al Qaeda in Iraq and helped U.S. troops target AQI.

Abu Bakr

The killings are doing what AQI wants: creating more distrust between Sunnis and the Shiite-led government, Mr. Mardini said.

“Some Awakening members have argued that Baghdad is allowing the attacks to occur as it lags to find employment for the Sunni fighters,” Mr. Mardini wrote in an analysis.

AQI has been able to find a new leader each time U.S. and Iraqi raids kill its chiefs.

The current leader is Abu Bakr al Baghdadi, whom the State Department in October added to its list of designated global terrorists and put up a $10 million reward for information leading to his killing or capture. After Navy SEALs killed bin Laden in May, Abu Bakr vowed to launch more than 100 attacks in Iraq, which continue to this day.

With the State Department’s designation, Abu Bakr has reached the terrorist status of al Qaeda leader Ayman al-Zawahri and Afghan Taliban leader Mullah Mohammed Omar.

The Obama administration, however, is downplaying the chances that Abu Bakr can return AQI to its high rate of killings in 2006 and 2007.

“There are very few indications that AQI has taken advantage of the withdrawal of U.S. forces to make major improvements to its organization,” said the U.S. official, who provided the assessment to The Times anonymously because of the subject’s sensitivity. “Although AQI terrorist activity is higher this year than it was in the last six months of 2011, it is well within the normal levels of violence that we have seen since 2010.”

Kenneth Katzman, a Middle East analyst at the Congressional Research Service, said there is not enough evidence to show AQI is back on top.

“We had these attacks even when we were there,” Mr. Katzman told The Times. “To say they are making a comeback, I think, is not that accurate a way of describing it.

“They never were completely defeated and now they’re acting. And they did act when we were there. I think what it is, is they may see more freedom of action now that we’re not there. They may feel they have more political support from the Sunnis to go after the government now.”