Foreign ministers from at least a dozen nations plan to gather in Vienna on Friday as part of a reinvigorated diplomatic push to end the Syrian civil war, now in its fifth year.
Few expect major breakthroughs, but the list of participants — including archrivals Iran and Saudi Arabia, long entrenched on opposing sides of the Syrian conflict — has generated some hope of jump-starting a peace process.
Secretary of State John F. Kerry this week called Vienna "the most promising opportunity" for a political opening on Syria. But he nonetheless labeled the challenge of navigating the obstacles ahead as "nothing less than to chart a course out of hell."
The conflict has left more than 200,000 people dead, caused vast destruction and left much of the country in the hands of hard-core Islamic militants, while also forcing more than 4 million Syrians to leave the country.
The Vienna talks starkly illustrate how Syria's fate is largely in the hands of foreign stakeholders. No one is scheduled to be present from the government of Syrian President Bashar Assad or from the disparate Syrian opposition, which includes armed extremists and peaceful activists in and outside the country.
In a major change, the Obama administration in recent weeks set aside its policy of trying to sideline Iran on Syria and went along with Tehran's participation in the Vienna talks. The concession seemed to signal a more pragmatic approach by Washington.
Iran has won global recognition as a crucial player on Syria, a sign of its growing diplomatic weight in the aftermath of the July agreement with world powers on its nuclear program.
The White House shift on Iran points to a sense of diplomatic urgency at a moment when the effects of the Syrian war are radiating far beyond the nation's borders.
Two relatively recent developments — the ongoing European refugee crisis and a monthlong Russian air campaign on behalf of the Assad government — appear to have added impetus to global efforts aimed at ending the intractable conflict.
European leaders, confronting their worst migration crisis since World War II, have joined the chorus calling for a negotiated end to the Syrian war, which has generated many of the multitudes of migrants descending on Europe. The once faraway conflict has become a stark reality for many European nations as asylum seekers besiege their borders.
The European Union faces "the risk of disintegration" if it fails to respond to the migration crisis, Federica Mogherini, the EU foreign policy chief, said Thursday, according to an Italian newspaper. But further flows of refugees from Syria will complicate efforts to craft any response.
The problem facing the Syria negotiations "is that key nations' bottom lines just don't overlap," Cliff Kupchan, chairman of the Eurasia Group political risk consulting firm, wrote in a report Thursday.
President Obama has declared that Russia's intervention in Syria is "doomed to failure," though Moscow's intense bombardment of rebel positions appears to have provided a military and psychological boost for Assad's forces.
Washington's stated view is that propping up Assad will only prolong the conflict. Moscow says that bolstering Assad and defeating "terrorists" arrayed against his government will hasten a democratic transition in Syria.
Assad's future remains the most incendiary issue in the debate on Syria.
Washington and its allies, including Saudi Arabia and Turkey, have not backed off from their insistence that Assad leave office. In recent weeks, though, all have said Assad could remain for the short term as part of a future "transitional" government.
While somewhat toning down the "Assad must go" demand, U.S. officials appear to believe that a diplomatic settlement excluding him from future office will ultimately be achievable through a combination of talks and expanded military aid to the Syrian leader's opponents. The strategy has not worked to date.
Assad's major allies, Russia and Iran, insist his fate should be decided by the Syrian people, perhaps in future elections. Moscow and Tehran appear to believe that their growing military presence in Syria will give them a stronger hand to dictate the shape of any future agreement.
At a briefing Thursday, White House Press Secretary Josh Earnest didn't promise success for the talks, saying that Kerry's goal was simply to test whether the Iranians and Russians would be willing to use their considerable influence on Assad to end the war.
"It's unlikely that it will be clear right away," Earnest said, adding that "to exclude Iran and Russia from the conversations would be a missed opportunity."
All participants in Vienna have embraced certain core principles, including the need to preserve the Syrian state and its institutions while defeating an array of Islamist terrorist groups, including Islamic State, the breakaway Al Qaeda faction that now controls territory in Syria and neighboring Iraq.
Kerry and others have said such "common ground" should engender confidence that a settlement may be achievable.
If negotiations fail, however, the risks of a stepped-up proxy war reminiscent of the conflict in Afghanistan in the 1980s are evident. Washington and its allies could bolster support for Syrian rebels, which could cause Russia and Iran to step up aid for Assad.
Syria could sink further into the abyss. Whether Vienna signals the beginning of the end of the Syrian tragedy or just provides the latest empty declarations in an ornate European hotel remains to be seen.
McDonnell reported from Beirut and Richter from Washington.