Story highlights CNN obtained audio of a conversation Kerry had with Syrian civilians

The meeting was on the sidelines of the UN General Assembly

Editor's note: CNN has taken down the audio recording at the request of some of the participants out of concern for their safety.

Washington (CNN) Secretary of State John Kerry's frustration with the failure of American diplomacy was on display as he defended US efforts to help end the five-year civil war in Syria during a meeting last week with a group of Syrian civilians, according to an audio recording obtained by CNN.

But Kerry also expressed sympathy for the Syrians' demands that the United States intervene more forcefully amid Syrian and Russian airstrikes against civilians, telling the group that he "lost the argument" for using military force against the regime of Syrian President Bashar al-Assad.

Kerry's comments came at a meeting that took place at the Dutch Mission to the United Nations on the sidelines the UN General Assembly, where Kerry was going from session to session in a frenzied effort to resuscitate a ceasefire that seemed poised to collapse.

"I think you're looking at three people, four people in the administration. I lost the argument. I've argued for the use of force. I'm the guy who stood up and announced that we're going to attack Assad for the use of weapons," Kerry is heard telling the Syrian attendees, referring to internal deliberations within the administration of President Barack Obama that followed Assad's use of chemical weapons in 2013.

Kerry also faulted Congress for failing to support such a retaliatory strike, saying, "The bottom line is that Congress refused even to vote to allow that."

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