Three vetoes of a UN Security Council resolution have left the major powers ready to bury Kofi Annan's peace plan.
UN Secretary General Ban Ki-moon stoutly insisted Saturday that he and special envoy Annan were still looking for ways to end a conflict that Syrian activists say has left more than 17,000 dead.
"We continue to push for a peaceful solution," Ban declared.
But the strife worsens.
Thousands are pouring across Syria's borders, Damascus is a city at war and the United States, European countries and the Syrian opposition now say they will look outside the Security Council for ways to pressure Assad.
While the rebel fighters in Syria remain relatively poorly armed, they are increasingly battle-hardened and their morale is being boosted by a growing number of defections from Assad's regime, diplomats say.
However, Russia and China's third veto of a Security Council resolution on Syria on Thursday was the death knell for joint UN-Arab League envoy Annan's six-point peace plan, according to many diplomats and experts.
The resolution, drawn up by Britain, sought to threaten sanctions unless Assad carried out just one provision -- to end the use of heavy weapons.
While everyone still professes loyalty to the Annan plan, the blame game over its demise started during the debate.
China's ambassador Li Baodong said unnamed countries had been "negative" about Annan's efforts since he started in February. And Russia accused the western countries of seeking a "military intervention" in Syria even though the United States, Britain and France insist they see no way for a new Libya-style operation. US ambassador Susan Rice said the suggestion was "paranoid".
Many experts see lingering fallout from last year's Libya campaign -- when Russia and China believe they were tricked into allowing a UN-backed military operation -- in the current battle over Syria.
"The Russians and the Chinese feel that sanctions was a code for regime change and to some extent they were right," said Mats Berdal, professor of security and development at Kings College's War Studies department in London.
"They are not going to give an inch in this case, and that made it very difficult."
The West in turn blames Russia for blocking appeals by Annan to impose "consequences" for not carrying out the plan which called for a halt to violence as a first step to political talks.
The failure "is no great loss" as it never had a chance of being accepted, said Richard Haass, president of the Council on Foreign Relations, a Washington-based think tank.
"It would be far better to terminate this effort and establish a new one with the mission of bringing about the exit of the current Syrian regime," he said.
Richard Gowan, associate director at New York University's Center on International Cooperation, said that "a mixture of dishonesty, intransigence and incompetence has created a disaster."
"The developments in Damascus and New York now make it clear that the outcome of the Syrian civil war will be decided on the battlefield rather than at the Security Council," he said.
Some Syrian opposition groups have publicly condemned Annan's efforts while the main powers have been wary of it for weeks, and it has foundered.
Annan "struggled to shore up his position with renewed overtures to Assad, the Russians and Syria's friends in Iran," according to Gowan.
"His courting of Iran infuriated US officials," he said, noting that the special envoy nevertheless "deserves credit for keeping up his efforts to find an impartial political solution in the face of almost impossible odds."
But "it would be understandable -- and perhaps wise -- if he were to stand down after this week's events," Gowan added.
Berdal, at Kings College, said Annan's problems were inevitable "with the Security Council as deadlocked as it is, with the Russians so determined not to give in at all in terms of putting some kind of pressure."
"He has done as best as he can in a very difficult situation," said Berdal.
"Some people thought he went too far with the regime. But he always saw that as a first step to moving the process forward and possibly finding some kind of face-saving formula for Bashar al-Assad to leave," he added.