Syria, by contrast, is hurtling ever deeper into an all-out conflict with no end in sight, “and all we get is words,” said Yasser Abu Ali, a spokesman for one of the Free Syrian Army battalions in the town of al-Bab, which lies 30 miles northeast of Aleppo.

The rebels say they don’t want direct military intervention in the form of troops on the ground. But they have repeatedly appealed for a no-fly zone similar to the effort that helped Libyan rebels topple Moammar Gaddafi last year and for supplies of heavy weapons to counter the regime’s vastly superior firepower, say rebels and opposition figures.

When the regime falls, as the rebel battalion spokesman assumes it eventually will, Syrians will not forget that their pleas for help went unanswered, he said.

“America will pay a price for this,” he said. “America is going to lose the friendship of Syrians, and no one will trust them anymore. Already we don’t trust them at all.”