U.S. Defense Secretary Leon Panetta defended the Obama administration’s decision not to arm the Syrian opposition, saying the country risked being pushed into an all-out civil war if efforts to secure a smooth political transition fail.

“We made a decision not to provide lethal assistance at this point. I know others have made their own decisions,” Panetta said in an interview on Thursday.

“But I think it’s very important right now that everybody focus on a smooth and responsible political transition,” he said.

“If we don’t get this done in a responsible way, there’s a real danger that the situation there could deteriorate into a terrible civil war.”

The defense secretary also said the United States was concerned about the possibility that shoulder-fired anti-aircraft missiles, known as MANPADs, stolen from Libya last year during the fall of Muammar Gaddafi, could make their way to Syria. He cautioned, however, that he had seen no direct intelligence yet to confirm those fears.

Panetta also expressed confidence that Syria’s chemical weapons stockpiles were not at risk.

“We’re confident that these sites are being secured. And we see no evidence that any of them are in jeopardy of being violated,” Panetta said.

The outside world is deeply divided in its response to an increasingly sectarian conflict in Syria that threatens to become a proxy war for regional powers. The United Nations estimates more than 10,000 people have been killed in 15 months of violence and unrest. Western diplomats say that month-old estimate is obsolete and the figure is likely much higher now.

Western nations and their Sunni Muslim allies in the Gulf and Turkey seek the overthrow of President Bashar al-Assad but are wary of direct intervention, while Russia, China and Shi’ite Iran - Assad’s strategic ally - have protected Assad from a tough international response.