U.S. Secretary of State John Kerry said on Friday that President Barack Obama had again asked for policy options on Syria but that none have yet been presented to him.

Kerry told reporters Obama was concerned about the deterioration in the humanitarian situation in Syria and also by the fact that peace talks between the opposition and government had not produced a discussion of a transitional government as had been planned.

As a result, Kerry said, "he has asked all of us to think about various options that may or may not exist."

"The answer to the question: have they been presented? No, they have not. But that evaluation, by necessity, given the circumstances, is taking place at this time," Kerry said. "And when these options are ripe and when the president calls for it, there will undoubtedly be some discussion about them."

White House spokesman Jay Carney said in Washington that Obama expected his national security team to constantly re-evaluate policy options on Syria and other issues.

"Secretary Kerry was reiterating what has always been the case, which is that the president is always looking at options on policy matters like Syria," Carney said. "This is not a one-time thing. It's not like this is a new review."

One U.S. official said the reviews reflect a months-long effort to try to find a solution to the civil war in Syria, in which the United Nations says more than 130,000 people have died since fighting began three years ago.

Obama, whose presidency has been marked by getting U.S. troops out of the war in Iraq and winding down their presence in Afghanistan, has declined to use U.S. military force in Syria and has been cautious about arming the moderate opposition.

At a news conference with French President Francois Hollande in Washington on Tuesday, Obama said "nobody is going to deny that there's enormous frustration here" over events in Syria and he suggested that he might be rethinking his policy.

"Right now we don't think that there is a military solution, per se, to the problem," he said. "But the situation is fluid, and we are continuing to explore every possible avenue to solve this problem."