President Barack Obama has ordered the urgent deployment of nearly 300 more armed troops to protect the United States Embassy in Iraq as Sunni militant fighters close in on Baghdad.
He has also directed his officials to consider all options to defeat the insurgents, but the stark reality remains that every option carries grave risks for both the US and Iraq, and none offers a speedy outcome.
The outlook is grim as the Islamic State in Iraq and the Levant (ISIL) has scored stunning victories, drawing to its ranks fighters from among Iraq's Sunni Muslims, who feel alienated by the sectarian policies of its Shi'ite Prime Minister Nouri al-Maliki.
But that does not make ISIL invincible. It will find it hard to occupy Baghdad, a city of nine million inhabitants, most of whom are Shi'ite, and many of whom are heavily armed.
The risk, therefore, is not that rebels will take over Iraq, but that ISIL will tighten its grip over the Sunni areas and establish a permanent sectarian dividing line.
"If military developments in Iraq conform to this most likely scenario, they could lead to a protracted, bloody stalemate," wrote Mr Kenneth Pollack, a veteran Middle East expert with the Brookings Institution in Washington. And once this happens, he warned, "the fighting will probably continue for years and hundreds of thousands will die".
In order to prevent this outcome, the US must assist Iraqi government forces in at least keeping the sectarian dividing line fluid enough to prevent it from becoming quasi-permanent. But that is easier said than done.
Drones, which have become the weapon of choice for the Obama administration, are useless: They depend on accurate intelligence information about the rebels, which currently does not exist, and cannot be used to push back large enemy formations.
The Americans have plenty of aircraft with their Fifth Fleet in the Gulf. However, air strikes risk heavy civilian casualties, with more than one million internally displaced Iraqis now on the move. While a more powerful weapon than drones, fighter jets on their own cannot regain territory.
That can be accomplished only by "boots on the ground", troops willing to confront ISIL fighters. But the Iraqi military, already in disarray, is now preoccupied with defending the Shi'ite hinterland from where most of its officer corps originates. And, apart from the possible and occasional use of special forces, Mr Obama has ruled out the introduction of any US ground troops.