"The regime is crumbling," State Department spokesman Patrick Ventrell said.

In Aleppo, the rebels are exceeding the expectations of military experts. Despite intense bombardment from warplanes, they've now withstood two weeks of regime counterattacks and are clawing toward the city center. Militiamen also are stepping up guerrilla-like forays in central districts of Damascus once firmly in Assad's hands.

Those gains have given the Obama administration hope that the tide of the war is turning — and without the need for the U.S. to reconsider its opposition to airstrikes, no-fly zones or even weapons sales to the anti-Assad forces.

And with U.N. special envoy Kofi Annan quitting his diplomatic efforts and the rebels starting to carve out larger toeholds in Syrian territory, the U.S. focus has changed accordingly.

Whereas once the U.S. hoped to see a cease-fire to end the fighting and