A new round of Syrian peace talks, unfolding as the nation's conflict marks its fifth year, opens Monday in Geneva with both sides as deadlocked as ever on a core issue: the future of Syrian President Bashar Assad.
In Paris, U.S. Secretary of State John F. Kerry on Sunday called the renewed talks "a moment of truth."
The talks are beginning as a fragile, 2-week-old "cessation of hostilities" holds in Syria, reducing violence by 80% to 90%, according to the U.S. State Department. The partial cease-fire represents the most sustained curb in violence since the conflict erupted in March 2011.
The limited truce has also allowed for deliveries of food and other humanitarian aid to tens of thousands of Syrians in besieged communities, the United Nations says.
The conflict has left much of Syria in ruins, destabilized neighboring nations, and forced almost half the country's prewar population of 23 million from their homes, spurring Europe's worst refugee crisis since World War II. Estimated death tolls range from at least 200,000 to more than 300,000.
The war also produced a new generation of Sunni Muslim militants who pose a global threat.
Diplomats view both the limited cease-fire and resumed aid deliveries as key confidence-builders that could provide momentum to a long-stalled negotiations process.
But even before the scheduled start of the U.N.-sponsored negotiations, the opposition and Damascus have staked out apparently irreconcilable positions on Assad's fate.
The main opposition bloc in Geneva, the Saudi-based High Negotiations Committee, has made it clear that it views Assad's departure as obligatory for any move toward a U.N. blueprint for a "transitional" government in Syria.
"We consider that the transitional period starts with the fall of Bashar al Assad or his death," Mohammed Alloush, the committee's chief negotiator, told reporters Saturday in Geneva.
In Damascus, the government declared that Assad's future was not up for negotiation, and chided Staffan de Mistura, the U.N. special envoy, for suggesting that new presidential balloting should be held within 18 months.
"Neither he [the U.N. envoy] nor anyone else has the right to talk about presidential elections," Syrian Foreign Minister Walid Moallem said at a news conference in Damascus, the Syrian capital.
The fundamental dispute about Assad's future helped scuttle U.N.-backed talks two years ago in Switzerland. Last month, a new series of Geneva talks was suspended before substantive talks ever began. Many are skeptical that this week's sessions will be any more successful.
Still, a generalized sense is evident among many diplomats that the war has gone on too long and done far too much damage — fanning the European refugee crisis and producing Islamic State, the Al Qaeda breakaway faction that controls territory in Syria and neighboring Iraq. Islamic State has been linked to deadly attacks in Paris; Ankara, Turkey; and Beirut, as well as the downing of a Russian airliner over Egypt.
"All of us have come here united in our deep belief that the Syrian civil war must end," Kerry said during a meeting in Paris on Sunday with a number of his European counterparts. "It is our sense that this is a moment of truth."
In recent months, the Obama administration has modified its demands that Assad step down at the start of any interim governing process, conceding that he may remain on the scene for some indeterminate period, though he would have to leave office eventually, the U.S. says. In December, Kerry declared in Moscow that the United States was not seeking "regime change" in Damascus.
In Paris, Kerry blamed Damascus for trying to sabotage the talks, but said the process must go forward. Both Russia and Iran, key patrons of the Syrian government, have backed the need for a political "transition" and new presidential elections in Syria, Kerry noted.
Not included in the ongoing cease-fire in Syria is Al Nusra Front, the Al Qaeda affiliate in Syria, and Islamic State. Hard-line Islamist factions have come to dominate the armed opposition fighting to overthrow Assad's secular administration.
Significantly, the Syrian cease-fire was brokered by officials in Moscow and Washington, who put pressure on their surrogate forces on the ground. Foreign sponsors will have to do a lot of the heavy lifting if a peace process is to be moved forward, analysts say.
"Expecting Syrians to come to terms among themselves is not productive," said Joshua Landis, a Syria expert at the University of Oklahoma. "The ideological, political differences between them are too great."
The Russian air offensive that began last fall has decisively shifted much of the battle in Assad's favor, giving Damascus less incentive to negotiate, many analysts say. In the opposition camp, many still seem to harbor hope that some kind of foreign intervention on their behalf may allow for a battlefield victory, however unlikely at this point.
The resumed talks will be "proximity talks," in which U.N. interlocutors visit the rival negotiating teams set up in different venues at the U.N. headquarters in Geneva. A political transition in Syria is at the top of the agenda, the U.N. says.
If the talks collapse, Kerry has hinted at a vague "Plan B," possibly involving a partition of Syria — something that no major bloc in the multi-sided war has publicly backed.
"It may be too late to keep it as a whole Syria if we wait much longer," Kerry told the U.S. Senate Foreign Relations committee last month.
But De Mistura has said more violence would be the likely outcome should the talks falter.
"The Plan B as far as we can see is just a continuation of a horrible conflict that goes on and on," De Mistura said in an interview with the English-language division of Al Jazeera, the satellite network. "And you know who will be the real victims — the Syrian people."
Times staff writer Tracy Wilkinson in Washington contributed to this report.