The Syrian government apologized, but Turkey, which backs the anti-Assad opposition, and its Western allies appear to be seizing on the incident to ratchet up pressure on Assad. They put the matter before the U.N. Security Council, hoping for a resolution that includes wording on the “responsibility to protect,” a phrase that analysts said could create an opening for a Libya-like international military intervention.

Syrian opposition forces have long sought the imposition of a no-fly zone, but the United States has resisted any form of military intervention, and Syrian allies Russia and China have vetoed resolutions that could lay the groundwork for such a move.

In a roundabout way, Syria specialist Leila Hilal said, events with Turkey might pressure Assad enough for Brahimi’s team to wrest some concessions from a regime that’s otherwise shown itself to be intractable. However, she quickly added, there are still far too many variables to warrant a surge of optimism in a diplomatic solution, and she said Brahimi was wise not to give false hope.

“He’s looking long-term. He’s not going to come out with another unrealistic plan for which there’s no traction,” said Hilal, the head of the Middle East Task Force for the New America Foundation, a Washington research center. “There’s no sense that the opposition is going to back down on its insurgency, and Assad is not going to lay down arms.”

Brahimi’s own boss, U.N. Secretary-General Ban Ki-moon, has said both sides seem determined “to see the end by military means.” U.S. and other Western officials are similarly downcast about the prospects of a renewed diplomatic push.

With a deadlocked Security Council that’s unable to support Brahimi’s mission and a series of unfruitful meetings with regime and opposition delegates in recent weeks, it’s unclear to many Syrians why the United Nations is continuing to push diplomacy at all.

“We knew, of course, that Kofi Annan had the support of the Security Council and was unable to achieve anything. It’s obvious that Brahimi doesn’t even have the support of the Security Council, so I don’t think he can achieve anything at all in the near future,” said Radwan Ziadeh, a spokesman for the opposition Coalition for a Democratic Syria who met with Brahimi in New York last week.

An added wrinkle is the addition of jihadist and other rogue groups to the opposition struggle. With not even half the rebel militias operating under any semblance of a unified Free Syrian Army banner, analysts said, it would be exceedingly difficult for the opposition to guarantee that all forces would abide by a cease-fire even if Brahimi were able to negotiate one.

“It would be hard to enforce a comprehensive cease-fire for the insurgency at this point in time because of these (jihadist) brigades,” Hilal said. “They’ve formed and appear to be acting in an aggressive way that’s inconsistent with other brigades that appear to have a clearer military strategy.”

Frustrated with the Security Council’s deadlock, some Syrian dissidents are sidestepping Brahimi and pushing directly for U.S.-led action, though they said they didn’t expect any change in the U.S. reluctance to intervene until after the presidential election in November.

By then, they said, the death toll will be higher, the neighbors will be drawn in even more deeply, sectarian tensions will have hardened and no one can say how cohesive a force the rebels will be.

“When diplomacy fails, it’s time for the militarized front to take over,” Jouejati said. “Everybody hopes for a diplomatic solution. I don’t think Brahimi is going to be the one to do it, but he may surprise us all.”