"Right now, Bashar al-Assad has not engaged in the discussions along the promised and required standard that both Russia spoke up for and the regime spoke up for," Kerry said during a press conference in Jakarta with Indonesian Foreign Minister Marty Natalegawa.
He said Assad's team "refused to open up one moment of discussion" of a transitional government to replace Assad's regime.
"It is very clear that Bashar Assad is trying to win this on the battlefield instead of coming to the negotiating table in good faith," Kerry said
Kerry also had harsh words for Assad's allies in Moscow. "Russia needs to be a part of the solution and not be contributing so many more weapons and so much more aid that they are in fact enabling Assad to double down," he said.
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Russia has told the US it was committed to helping create a transitional government, Kerry said, but has not delivered "the kind of effort to create the kind of dynamic by which that could be achieved."
UN-Arab League mediator Lakhdar Brahimi apologised to the Syrian people for failing to reach progress. "I am very, very sorry, and I apologise to the Syrian people that their hopes which were very, very high that something will happen here," Brahimi said.
Syria's conflict started as largely peaceful protests against Assad in March 2011 but later degenerated into a civil war in which more than 140,000 people have been killed, according to activists.