The US is reluctantly being dragged back into the smouldering ashes of the Iraq War amid accusations that its failure to intervene in Syria aided the rise of jihadists now closing in on Baghdad.
More than a decade after the invasion and almost three years since the last US troops pulled out, Washington has been relegated to the sidelines as it watched Iraqi forces collapse in face of this week's surprise onslaught by the Islamic State of Iraq and Levant.
The US has poured more than $25 billion into training and equipping the Iraqi army since 2003, and even State Department spokeswoman Jen Psaki admitted there had been "a clear structural breakdown" among the security forces.
With Baghdad now in ISIL's sights as it seeks to establish an Islamic caliphate stretching from Lebanon to Iran's Zagros Mountains, Washington is vowing to ramp up military aid.
The Obama administration is even mulling an Iraqi request for drone strikes -- something it has consistently refused.
A demand for an additional $1 billion of US military aid to Iraq, including aircraft and some 200 Humvees, is already before US lawmakers.
It is out of the question however that President Barack Obama, who won his first term in 2008 on a platform of ending the wars in Iraq and Afghanistan, will send American forces back to the battlefields where some 4,500 were killed.
"ISIL can certainly keep their expansion going, the question is when will they hit a brick wall," said Michael Rubin of the American Enterprise Institute.
Both the US intelligence services and the Iraqi authorities were caught "flat-footed," Rubin told AFP, adding that "no one saw this insurgency coming with the speed that it did."
As the White House huddles in crisis talks, the easiest option now facing Obama is to send in military advisors "to help the Iraqi army to do better with what they have. That's the least problematic," said retired major general Paul Eaton from the National Security Network think-tank.
"The next (option) would be some kind of air-delivered capability either drones or aircraft. But there are some political downsides to that... just the image of America bombing Arabs is not a great image."
Neither of those two moves, however, would help restore the credibility of the Iraqi army.
"What Western armies do best is to teach people how to fight," Eaton said, calling for more and better training even though US forces have been working with Iraqi soldiers in Jordan since earlier this year.
Chaos of Arab Spring
Aside from the inherent weaknesses of the Iraqi security forces, analysts highlighted that the country had come under enormous strain from the war in neighboring Syria.
One of the causes behind the turmoil in Iraq "is an exogenous shock, which is clearly the Arab Spring," RAND Corporation senior political scientist Christopher Chivvis said, highlighting that the events had coincided with the withdrawal of US forces.
"Without the Arab Spring, it's much less likely that you would see this deterioration in Iraqi security that we have today."
Psaki agreed, telling reporters "this a situation where the impact of the ongoing crisis in Syria, the overflow of that into Iraq, has clearly been a major factor."
Many of the ISIL fighters, who split from Al-Qaeda last year, have been trained in arms and warfare in Syria and US lawmakers Thursday put the blame squarely on the administration's lack of a regional strategy.
Hawkish Republican senator John McCain called for "drastic measures" to reverse the sweep by the Sunni militants.
"Get a new national security team in place. You have been ill-served," he stormed.
But since 2011, the Obama administration has sought to portray the situation in Iraq as a problem for the Baghdad government, repeatedly urging Shiite Prime Minister Nuri al-Maliki to work harder to foster unity and reconciliation.
"US officials are right to place part of the blame for this on Nuri al-Maliki," argued Faysal Itani, a fellow with the Atlantic Council.
He called for serious pressure on Maliki "to reconcile with more mainstream aggrieved Sunni militants and tribes cooperating with ISIL, without whom ISIL would not have been able to make such swift, massive territorial gains."