Washington and Moscow inched toward agreeing on a renewed cease-fire in Syria but fell short of announcing a deal after a daylong meeting between top diplomats in Geneva on August 26.
"We are close," said U.S. Secretary of State John Kerry after the 12-hour talks. "But we are not going to rush to an agreement until it satisfies fully the needs of the Syrian people."
Kerry said "we achieved clarity on the path forward" for a revamped cessation of hostilities, adding that the "vast majority" of technical obstacles to a cease-fire were cleared but some issues remained unresolved.
Russian Foreign Minister Sergei Lavrov echoed his American counterpart, telling reporters that "very important steps" had been made on a deal to stop the violence.
"I think in the nearest time we will present the fruits of our joint efforts," Lavrov said.
There had been hopes of a definitive announcement to stem the fighting in the war-torn country and on proceeding to a new round of UN-brokered peace talks.
But Kerry stressed that they didn't want to announce an agreement prematurely, only to watch it fall apart as happened with a previous cease-fire brokered by Moscow and Washington in February.
"We do not want to make an announcement...that is not enforceable, that doesn't have details worked out, that winds up in the place that the last two announcements have wound up," Kerry said.
"Until we have, neither of us are prepared to make an announcement that is predicated for failure. We don't want a deal for the sake of the deal, we want a deal that is effective...and that works for the people of Syria, that makes the region more stable and secure, and that brings us to the table here in Geneva to find a political solution."
Kerry said U.S. and Russian experts would continue to meet in Geneva in the coming days to try to iron out remaining obstacles to a durable deal.
Lavrov said one of the unresolved issues is the possibility of coordinating air strikes against the Islamic State and other terrorist groups in Syria.
On that point, he said the United States has not fulfilled its promise to separate the rebel groups it supports from Al-Nusra Front, Al-Qaeda's Syrian affiliate, which has been fighting side by side with U.S.-backed forces.
"Without a delineation between normal, healthy opposition forces and terrorists, I see no possibility of reaching a long-term and comprehensive cessation of hostilities," Lavrov said.
Kerry said the United States is seeking to enlist neighboring countries that have influence in Syria to help separate rebel forces from the Al-Nusra group, which recently renamed itself Fateh Al-Sham Front and renounced its affiliation with Al-Qaeda.
Kerry said neither Washington or Moscow is deceived by the name change. "Nusra is Al-Qaeda, and no name change by Nusra hides what Nusra really is and what it tries to do."
While the United States has been providing financial support, training, advice, and some air power back-up to Syria's main opposition alliance, Russia has provided diplomatic support and air power back-up to Syrian regime forces.
Kerry listed two main requirements to ensure a revamped cease-fire holds: unified responses to cease-fire violations by the Damascus regime, and checks on the rising influence of the Al-Nusra group.
The two diplomats were briefly joined by United Nations envoy for Syria Staffan de Mistura, who said he hoped the talks would revive peace negotiations that were last held in April.
Successive rounds of negotiations have failed to end a five-year civil war that has killed more than 290,000 people, forced millions from their homes, and fed an unprecedented migrant crisis in Europe.
Both Kerry and Lavrov stressed the need for fresh talks to find a political solution to the crisis.
Kerry voiced hope that reestablishing a geniune cease-fire could "open the window of opportunity for us to be able to get to the table here in Geneva, and have a real negotiation about the future."
The most immediate concern of all sides is the need for humanitarian aid for millions of civilians in the besieged city of Aleppo, which has been the focal point of fighting much of the year.
The UN on August 26 described the lack of humanitarian access as "wholly unacceptable," saying just one aid convoy had completed deliveries this month.
Russia last week gave its blessing to a weekly pause in fighting in Aleppo for 48 hours to allow aid in, but de Mistura said other unspecified parties are still blocking an agreement.
Meanwhile, in a blow to opposition forces, rebels and civilians in the besieged Damascus suburb of Daraya were evacuated on August 26 after agreeing to surrender the town after four years of grueling bombardment and a crippling siege that left the sprawling area in ruins.
The surrender of Daraya, which became an early symbol of the nascent uprising against Syrian President Bashar al-Assad, marks a success for his government, removing a persistent threat only a few miles from his seat of power.
Lavrov said the Daraya surrender is "an example I think will get some following." He said the Russian military's reconciliation center in Syria has received a request from another area to organize a similar operation -- with Russian mediation.