In the past week, the rebels have seized five important military facilities in the north, the east and near the capital, Damascus, capturing sizable quantities of weaponry, further isolating remaining government positions and freeing opposition fighters to focus on attacking Assad’s forces…

The fighting is piecemeal, intense and likely to persist for many more months as regime troops and rebel fighters battle it out town by town and base by base across the vast swaths of the country that are being contested. But no longer is it possible to describe the war in Syria as a stalemate, said Jeffrey White, a defense fellow at the Washington Institute for Near East Policy, and the pace of rebel gains in recent weeks raises the prospect that a collapse of government forces could come sooner than has been expected.

“The war is turning against the regime, and it’s turning at a faster rate than we had seen before,” White said. “There’s a reasonable chance there will be some kind of breaking point, and the regime will collapse in a hurry. It’s not probable, but it’s possible, and then the guys with the guns will be in charge.”