A resurgence of violence and advances by al Qaeda fighters in Iraq, Syria and Lebanon is providing new evidence undermining White House claims that the terrorist group is on the run and prompting fresh scrutiny of President Obama's decision not to leave a residual level of troops in Iraq.

Faced with news that al Qaeda fighters had taken control of the city of Fallujah in Iraq's Anbar province and were fighting against Syrian rebels they had previously joined, U.S. officials Monday pledged support to the Iraqi government while committing very few American resources to the task.

Top White House and State Department officials on Monday put much of the onus for sorting out the sectarian violence and divisions on the Iraqis, even as they pledged limited military support — additional weapons but no troops — to Iraqi Prime Minister Nouri al-Maliki.

“This is something for the Iraqis to take the lead on and handle themselves,” White House press secretary Jay Carney said, quickly adding, “That doesn't mean we cannot assist them.”

Carney was echoing Secretary of State John Kerry's statements over the weekend that Iraq's growing al Qaeda problem is “their fight.”

State Department spokeswoman Marie Harf said Monday the U.S. is “standing with” the Iraqi government in this fight and is planning to accelerate its supply of Hellfire missiles as “early as this spring,” adding to the 75 it already provided in December. In the coming weeks, the U.S. also will hand over 10 surveillance drones and 48 more by the end of the year, she said.

But Harf made it clear that the administration viewed the spiraling violence in Iraq and Syria as mainly an Iraqi problem to solve.

“When we left Iraq at the end of 2011, Iraq had an opportunity and they still have an opportunity to move away from violence, to choose their future,” she said.

Vice President Joe Biden called Maliki Monday night to express concern for “those Iraqis who are suffering at the hands of terrorists” and to praise the renewed security cooperation between the Iraqi army and local and tribal forces in Anbar province, the White House said.

Biden and Maliki agreed to continue “to deepen” the U.S.-Iraq security partnership.

Foreign policy experts believe the region has grown so unstable the Iraqi government may be incapable of regaining control of certain regions. Baghdad, they worry, is tilting toward civil war, and al Qaeda could establish control over its own loose state in the area where it would be free to plot attacks on the U.S. and others.

Christian Whiton, a former Bush State Department senior adviser and the author of “Smart Power: Between Diplomacy and War,” bemoaned a lack of U.S. leadership in Iraq that allowed Iran an open door to influence Maliki, a Shiite, to consolidate power against the Sunni minority.

In an effort to seize more power early in his tenure, Maliki accused his own Vice President, Tariq al-Hashemi, of terrorism, forcing him to flee the country to avoid arrest and Sunnis to feel even more disenfranchised without a senior representative in the the government.

Whiton said the Obama administration, led by Biden, didn't try hard enough when negotiating the Status Force Agreement with Iraq to push for a residual level of U.S. troops.

He said the U.S.-Iranian deal to lift international sanctions in exchange for Tehran freezing its nuclear program is only a distraction for Iran's efforts to gain additional influence in the region.

“So now we have a revival of the Sunni-Shiite divide and Iraq has become a playground for what Iran is up to — and we're distracted with this phony agreement with Iran,” he said.

Many U.S. lives were lost when sectarian violence and and al Qaeda roiled the Anbar region during the middle of the Iraq war, but the 2006-2007 surge of U.S. troops stabilized the region.

Carney, however, said leaving a residual number of U.S. troops in Iraq wouldn't make a difference.

“There was sectarian conflict with 150,000 troops in Iraq so the idea of this would not be happening if 10,000 troops had stayed, bears scrutiny,” he said.

Even some who supported a complete withdrawal of U.S. troops from the region say the Obama administration squandered an opportunity to play an influential role in the Middle East once the Iraq war was over.

Maj. Gen. Paul Eaton, a 30-year-Army veteran who served in Iraq, Bosnia and Somalia and is now a senior adviser at the National Security Network, said the administration could have done a much better job in laying out a firm “carrot-and-stick” approach to dealing with the aftermath of the war.

He said the administration also fumbled a major opportunity when it failed to follow former U.S. Ambassador to the United Nations Richard Holbrooke's vision for developing a regional strategy ahead of drawing down troops in Afghanistan.

In early 2009, Obama appointed Holbrooke as a special representative to Afghanistan and Pakistan, but he passed away suddenly the following year.

“I think the world of [Secretary of States Hillary] Clinton and John Kerry,” Eaton said. “But I do not believe the president has thrown his weight into the mix to achieve better outcomes.”

“The solution was a political-diplomatic solutions but we did not apply the full power that American diplomacy holds,” Eaton added.