Surprise talks between US Secretary of State Hillary Clinton, her Russian counterpart Sergei Lavrov and the UN peace envoy to Syria ended without any "sensational decisions" to halt the conflict.
UN envoy Lakhdar Brahimi said all three agreed the situation was "very, very, very bad" in Syria during the 40-minute meeting in Dublin on the sidelines of an international gathering, but "no sensational decisions" were reached.
Amid fears the 21-month conflict may take a gruesome new turn and see the Syrian regime unleash chemical weapons, the three discussed "how we can work out hopefully a process that will get Syria back from the brink," Brahimi said.
The United States has been urging Russia to use its leverage with Syrian President Bashar al-Assad to try to open the way towards a political transition, although Washington has insisted the long-time leader will have to go.
A US State Department official said it was "a constructive discussion" and that the "next step will be a meeting in the next few days between special envoy Brahimi and senior officials from the United States and Russia to discuss the specifics of taking this work forward."
US officials had hoped Lavrov was signalling a new willingness by Moscow, a staunch Damascus ally, to probe ways to bring more pressure to bear on Assad to step down by accepting Brahimi's invitation to the talks.
Brahimi told reporters afterwards the three agreed to put together a peace process that will be based on the Geneva accord, which was adopted under the previous joint UN-Arab League envoy Kofi Annan.
Moscow initially signed onto the six-point plan crafted by Annan, but then balked in the face of imposing punitive UN action if Syria refused to implement it.
Brahimi vowed "to continue to discuss this with other countries present in Geneva, and also all the countries as I've said with interest or influence in Syria. We haven't taken any sensational decisions".
"But I think we have agreed that the situation is bad and we have agreed that we must continue to work together to see how we can find creative ways of bringing this problem under control and hopefully starting to solve it," he said.
Clinton told reporters shortly before the talks: "We have been trying hard to work with Russia to stop the bloodshed in Syria and start a political transition toward a post-Assad Syrian future."
"And we very much support what Lakhdar Brahimi is trying to do. Events on the ground are accelerating and we see that in many different ways," she added.
The three-way talks took place on the sidelines of a meeting of the Organization for Security and Cooperation in Europe (OSCE).
They came amid growing concern the Assad regime may be preparing to use chemical weapons as it battles opposition rebels.
Clinton on Wednesday renewed Washington's vow to find ways to provide fresh support for the Syrian opposition, which has come together in a new body known as the Syrian National Coalition.
Washington has so far provided humanitarian aid to the rebels, but refused to arm the opposition amid fears of pouring weapons into an already volatile region, where anti-US militant groups are springing up.
Clinton also warned Damascus again that any use of chemical weapons against rebel forces was a clear red line that must not be crossed.
"Our concerns are that an increasingly desperate Assad regime might turn to chemical weapons or might lose control of them to one of the many groups that are now operating within Syria," she told reporters after a NATO meeting.
But she again pressed the Assad regime to make "the decision to participate in a political transition, ending the violence against its own people."
The Dublin talks come ahead of a key meeting of the Friends of the Syrian People in Marrakesh next week, which Clinton will attend.
It is likely the United States will move towards recognising the Syrian National Coalition as the legitimate representative of the Syrian people at the meeting, after France last month became the first Western nation to do so.