Russia, a major Syria backer that holds a veto on the Security Council, has consistently blocked any resolution that would create consequences in the form of economic or military pressure for Assad if he insisted on holding on to power. The resolutions that have been passed by the council either had no bearing on the political outcome of the conflict — for example, the deal brokered by Russia under which Assad agreed to give up his chemical weapons, and which gave the Obama administration an off-ramp from planned military strikes — or have been largely been ignored on the ground, as in the case of February’s resolution on humanitarian access.

But because the status quo in Syria is largely favorable to Russia’s strategic interests, the onus, when speaking of the international community’s role in changing Syria’s fortunes, invariably comes down to Washington’s policy.

“Until the U.S. is willing to talk to Assad, or willing to kill him, there’s not going to be any fruitful role for a peace mediator,” said Landis.

But “the West does not want to engage in that kind of mediation,” continuing to insist that Assad step aside as part of any negotiations, Landis said. Before the talks in Geneva in January overseen by Brahimi, Assad had openly stated his intention for standing for re-election later in the year, saying: “I see no reason why I shouldn’t stand.”

Brahimi’s biggest achievement may have been getting a group of opposition members and the Syrian government to sit down in two rounds of talks in Geneva. But the negotiations lasted less than a month and quickly fell apart. The only agreement of significance in Switzerland was a deal to provide relief to the besieged city of Homs and allow a number of holed-up civilians to leave the city.

While the subsequent cease-fire and civilian evacuation in Homs earlier this month was a rare bright spot for international efforts to increase humanitarian access in Syria, it also capped a string of Assad victories, leaving the already fragmented Syrian opposition reeling and returning what had been the “capital of the rebellion” back to government hands.

With the Syrian regime unencumbered by public opinion as it pursued a military solution that imposed a brutal toll on the civilian population, and backed by resolute international allies Russia and Iran, it has ridden a wave of tactical victories during the third year of the armed rebellion, with little on the horizon to suggest a change in the conflict’s military balance. The deck was stacked against Brahimi from the start, and the scenario doesn’t look any different for any replacement the U.N. may appoint.

The war grinds on unabated, its humanitarian consequences continuing to fester. Even as the U.S. makes some progress in easing tensions with Iran on the nuclear file, Tehran believes its Syrian ally has won the war. And the Ukraine crisis has made prospects for U.S.-Russian cooperation on Syria even more remote.

“Syria will continue to sort of exist in this stalemate,” Hashemi said. “The repercussions are going to affect the entire world.”