Major power foreign ministers failed to agree a new date to resume Syrian peace talks at a meeting on Tuesday, and the opposition said it would not come back to Geneva negotiations unless conditions improved on the ground.
A pessimistic atmosphere pervaded the meeting in Vienna between countries that support President Bashar al-Assad and his enemies, all of which have committed to reviving a cease-fire and peace process that have been unraveling since last month.
In a joint statement after the meeting attended by the United States, European, and Middle East powers that oppose Mr. Assad as well as Russia and Iran which support him, the powers called for a full cessation of hostilities and access for aid.
In stronger language than in the past, they warned the warring factions that if they repeatedly broke the truce they risked foregoing the protection of the Feb. 27 cessation of hostilities agreement sponsored by Washington and Moscow.
They also directed the UN's World Food Program to air drop food, medicine, and water to besieged communities starting on June 1 if humanitarian access was denied by either side.
But they did not agree on a date for peace talks to resume. The Geneva talks broke up last month after the opposition delegation quit, accusing the government of ignoring the cease-fire, and recent weeks saw an intensification of fighting, particularly near Aleppo, Syria's largest city before the war.
UN envoy Staffan de Mistura told a news conference there was still a strong desire to keep the peace process moving.
"We want to keep the momentum. The exact date I am not at the moment revealing it because it will depend also on other facts," he said. He noted that the Muslim fasting month of Ramadan, which begins in early June, was coming soon.
The main opposition High Negotiations Committee said it was not willing to return to negotiations without a full cease-fire and access for humanitarian aid.
"I don't think there will be results, and if there are any results they will not be sufficient for the Syrian people," HNC chief negotiator Asaad al-Zoubi told Reuters ahead of Tuesday's Vienna meeting.
"We are used to the fact that Russian and US foreign ministers are taking the world into an unknown direction," he said. "The HNC has said that if aid does not reach everybody, if the sieges aren't lifted and if a full truce does not happen, there will be no negotiations."
Despite the resigned outlook held by leaders at the meeting, if foreign powers can establish a true ceasefire and work with Assad on a government transition then solid results could follow. As The Christian Science Monitor noted in March, "A key next step is a full truce that can be monitored. Even though that means the conflict is simply 'frozen,' it provides the peace that will provide the opportunity for Syrians to decide if they want to keep their country whole or split it up. The hardest decision is whether President Bashar al-Assad will accept a transition process that ends his rule."
No Peace Without Settlement
Washington, which wants Assad to leave power, has worked closely on diplomacy with Russia, which joined the war last year to support him. That has alarmed some of Assad's opponents and raised doubts among some of the countries that support them.
US Secretary of State John Kerry, standing beside Russian Foreign Minister Sergei Lavrov and de Mistura at a news conference, made clear Washington still wanted Assad out.
Russia needed to use its influence over Assad to secure a transition in Syria, Kerry said.
"This war will not end for him or for his people without a political settlement."
Gesturing to Mr. Lavrov, Mr. Kerry said Assad had made a series of commitments to Moscow that he was prepared to negotiate, but had not kept his word.
"I think he should never make a miscalculation about President Obama's determination to do what is right at any given moment of time where he believes he has to make that decision," Kerry said.
Lavrov repeated Moscow's line, that it was not fighting on behalf of any particular ruler in Damascus: "We don't support Assad. We support the fight against terrorism."
France's Foreign Minister Jean-Marc Ayrault said progress was needed urgently on the ground.
"If nothing happens in terms of respecting the cease-fire or humanitarian aid, then it will no longer be about discouragement, but despair. We are in an extremely fragile period."
The United Nations said this month that Syria's government, which has been on the front foot in the war since its ally Russia intervened last year, was refusing UN demands to deliver aid to hundreds of thousands of people.
Tuesday's talks discussed ways to stop the violence by separating al-Nusra Front, al Qaeda's wing in Syria, from other opposition fighters in some areas like Aleppo.
Ayrault said France had told moderate opposition groups "they must be extremely clear with regard groups like al-Nusra. There must be no ambiguity."
Nusra, along with Islamic State, is not party to the cease-fire. Western and Arab states accuse the Syrian government and Russia of using links between rebels and Nusra as a pretext to launch offensives against other opponents of Assad.
De Mistura is trying to meet an Aug. 1 deadline to establish a transitional authority for the country that would lead to elections in 18 months, as agreed in a December United Nations Security Council resolution. Kerry said in Vienna that if progress in talks was made the timeframe would be respected.
Every diplomatic situation is unique, and outside violence from Nusra and IS complicate the outside peace process, but it should be noted that "since the end of the cold war, more conflicts have been resolved by peace settlements than by military victories."
Fate of Assad
However, the US administration's failure to convince Moscow that Assad must go is fueling European and Arab frustration at being sidelined in efforts to end the country's five-year civil war, diplomats say.
Saudi Foreign Minister Adel al-Jubeir said it was perhaps time to consider alternatives, including ramping up military aid to rebels, if Assad's government continued to flout international agreements.
In the past weeks, several hundred civilians have been killed in air strikes and rebel bombardments in Aleppo province alone, while fighting has taken place in other parts of Syria, including Idlib, Deir al-Zor and around Damascus.
As the talks took place, rebel fighters and officials in the besieged town of Daraya on the outskirts of Damascus said they believed government forces were preparing an assault.
Last week government forces refused entry to what would have been the first aid convoy to reach the town. Troops began shelling the town on Thursday, ending a lull that had prevailed since the ceasefire took effect. Residents say they are on the verge of starvation.
"Large convoys of (government) troops are moving from the airport and from Ashrafiyat Sahnaya (the next town south)," said Abu Samer, spokesman for the Liwa Shuhada al-Islam rebel group.
"We are prepared to repel their assault but our main fear is for the civilians besieged in the town who face severe shortages of food."
A Syrian military source denied rebel accounts of troop deployments, saying nothing had changed in the area.
The blocked aid convoy was not allowed to contain food, only medical and other aid, and residents launched an online campaign ahead of the expected delivery with the slogan: "We cannot eat medicine".
(Additional reporting by John Irish and Shadia Nasralla in Vienna and Suleiman al-Khalidi in Amman; writing and editing by Peter Graff and Peter Millership)